Australian Curriculum Science: Year 7 - Ages 11+ by Teacher Superstore

RIC-6700 7.6/1231

Titles in this series: Australian curriculum science (Foundation) Australian curriculum science (Year 1) Australian curriculum science (Year 2) Australian curriculum science (Year 3) Australian curriculum science (Year 4) Australian curriculum science (Year 5) Australian curriculum science (Year 6) Australian curriculum science (Year 7)

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This master may only be reproduced by the original purchaser for use with their class(es). The publisher prohibits the loaning or onselling of this master for the purposes of reproduction.

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Internet websites In some cases, websites or specific URLs may be recommended. While these are checked and rechecked at the time of publication, the publisher has no control over any subsequent changes which may be made to webpages. It is strongly recommended that the class teacher checks all URLs before allowing students to access them.

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Foreword Australian curriculum science – Foundation to Year 7 is a series of books written specifically to support the national curriculum. Science literacy texts introduce concepts and are supported by practical hands-on activities, predominantly experiments. All Science Understanding and Science as a Human Endeavour substrands for each level are included. Science inquiry skills and overarching ideas underpin all topics. Australian curriculum science is a complementary resource to the previously released R.I.C. series, Primary science. Titles in this series are:

Australian curriculum science – Foundation Australian curriculum science – Year 1 Australian curriculum science – Year 2 Australian curriculum science – Year 3

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Using chromatography ...................................................................... 69 What are some separation methods used around the home? .......70–72 Mixed-up food investigation .............................................................. 73

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Teachers notes ............................................................................ iv – vi Science inquiry skills overview ..................................................vii – viii Experiment format ............................................................................. ix Scientific method process ................................................................... x Investigation format ........................................................................... xi

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Australian curriculum science – Year 4 Australian curriculum science – Year 5 Australian curriculum science – Year 6 Australian curriculum science – Year 7

Earth and space sciences .......................................................74–121 What are the relative movements of the Earth, sun and moon? ..................................................................................74–76 Modelling rotation and revolution ..................................................... 77 Why do seasons occur on Earth? .................................................78–80 How do seasonal changes affect living things? ................................... 81 Why do phases of the moon occur? .............................................82–84 Observing the moon’s phases ............................................................ 85 What are solar and lunar eclipses? ..............................................86–88 Observing a solar eclipse .................................................................. 89 How have advances in telescopes and space probes helped astronomers? ...................................................................90–92 Comparing models of the solar system .............................................. 93 What are Earth’s resources? ........................................................94–96 What is the source of this resource? .................................................. 97 How long do resources take to regenerate? ...............................98–100 Oil, coal and gas will run out ... won’t they? .................................... 101 Which resources are used for energy? .....................................102–104 Energy alternatives for the future..................................................... 105 What is the water cycle?...........................................................106–108 Mini solar still experiment .............................................................. 109 What natural factors influence the water cycle? .......................110–112 Evaporation rate experiments.......................................................... 113 What human factors impact on the water cycle? ......................114–116 Aquifer experiment ......................................................................... 117 What are some advances in the treatment and management of water? .................................................................................118–120 Greywater and blackwater investigation........................................... 121

Biological sciences ....................................................................2–53 What is classification and why is it important? .................................2–4 Classifying living things........................................................................ 5 How are living things classified? ......................................................6–8 Classifying local species ...................................................................... 9 What are the hierarchical levels of taxonomy? .............................10–12 Ocean life taxonomy.......................................................................... 13 How has classification changed over time? ..................................14–16 The tree of life................................................................................... 17 How are living things named? ......................................................18–20 Scientific names of local species ....................................................... 21 How are unknown organisms identified? .....................................22–24 Create a dichotomous key to identify insects ..................................... 25 How do food chains show relationships in a habitat?...................26–28 Food chain representation ................................................................ 29 What are food webs and what do they show? ...............................30–32 Construct a food web ........................................................................ 33 What else do food webs show? ....................................................34–36 Plan a different energy pyramid of your own ..................................... 37 What part do microorganisms play in a food web? ......................38–40 Microcomposting .............................................................................. 41 What impact do humans have on the environment? .....................42–44 Calculate your carbon footprint......................................................... 45 What are some examples of human impact on the environment?.........................................................................46–48 The human impact of palm oil harvesting.......................................... 49 How can traditional and Western scientific knowledge help with managing the environment? .........................................50–52 Pollutant and fertiliser experiment .................................................... 53

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Physical sciences .................................................................122–141 What are Newton’s laws of motion?..........................................122–124 Water wheel experiment.................................................................. 125 How do balanced and unbalanced forces work? .....................126–128 Friction on different surfaces .......................................................... 129 What are simple machines? .....................................................130–132 Lifting with levers ............................................................................ 133 What does gravity do to things on Earth? .................................134–136 Does gravity work the same on all objects?...................................... 137 Why do planets go around the sun? .........................................138–140 Students in orbit.............................................................................. 141

Chemical sciences ...................................................................54–73 What are mixtures and pure substances? .....................................54–56 Using properties to identify substances.............................................. 57 What are solvents and solutes? ....................................................58–60 The effect of heating on solubility ...................................................... 61 How is separation used in the real world? ...................................62–64 Cleaning up oil spills ......................................................................... 65 How is separation used in food production?................................66–68

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Teachers notes Each book is divided into four sections corresponding to the four substrands of the Science Understanding strand of the curriculum. Shaded tabs down the side of each book provide a quick and easy means to locate biological sciences, chemical sciences, Earth and space sciences or physical sciences substrands. Science as a Human Endeavour units or questions, as set out in the Australian Curriculum, are included in all substrands. Science inquiry skills are included in all units. The skills utilised are listed on each teachers page. The six overarching ideas (Patterns, order and organisation; Form and function; Stability and change; Scale and measurement; Matter and energy; and Systems) underpin each science literacy text page and are included as much as possible throughout the comprehension pages. Each substrand is divided into a number of four-page units, each covering a particular aspect and following a consistent format.

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The four-page format of each unit consists of: • a teachers page

• student page 1, which is a science literacy text about the concept with relevant diagrams or artwork

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• student page 2, which includes comprehension questions about the literacy text • student page 3, which involves a hands-on activity such as an experiment.

Teachers page

The first page in each four-page format is a teachers page which provides the following information:

• The title of the four-page unit is given.

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• The content focus (the particular aspect of the unit covered in that set of four pages) is given.

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• The inquiry skills focus covered within the four pages is set out.

• Answers and explanations are provided where appropriate for student pages 2 and 3 (the comprehension questions relating to the text and the final activity in the set of four pages).

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• A shaded tab gives the Science Understanding substrand.

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FOUR-PAGE FORMAT

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• Preparation states any material or resources the teacher may need to collect to implement a lesson, or carry out an experiment or activity. • The lessons provides information relating to implementing the lessons on the following student pages.

• Background information, which includes additional information for teacher and student use and useful websites relating to the topic of the section, expands on the unit.

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Teachers notes FOUR-PAGE FORMAT (continued) Student page 1 The second page in the four-page format is a science literacy text which introduces the topic. This page provides the following information:

• A shaded tab down the side gives the Science Understanding substrand.

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• The title of the unit is given. This is in the form of a question to incorporate science inquiry skills and overarching ideas.

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• The science literacy text is provided.

• Relevant diagrams or artwork enhance the text, or are used to assist student understanding of the concepts.

Student page 2

The second student page consists of a series of questions or activities relating to the literacy text. They aim to gauge student understanding of the concepts presented in the text. Many of these questions relate to overarching ideas relevant to that age level as stated in the Australian Science Curriculum.

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• The title, which is the same as the text page, is given.

• A shaded tab gives the Science Understanding substrand.

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• Questions or activities follow. These relate to the text on the previous page.

Where relevant, a question relating to Science as a Human Endeavour may be included as the final question on this page. This assists in keeping the strands interrelated. This question is indicated by the icon shown to the left. R.I.C. Publications®

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Teachers notes FOUR-PAGE FORMAT (continued) Student page 3 The third student page provides a hands-on activity. It may be an experiment, art or craft activity, research activity or similar.

• A shaded tab gives the Science Understanding substrand.

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• The title is given. This will be different from the previous two pages, but will be a related to the concept focus of the unit.

• An adapted procedure for an experiment, craft activity or a research activity is given.

Science as a Human Endeavour units and questions

Those four-page units which are related specifically to Science as a Human Endeavour substrands are indicated by the icon shown.

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Where Science as a Human Endeavour questions occur within Science Understanding units, they are also indicated by the use of the icon. Explanations and answers relating to these questions are given on the appropriate teachers page.

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Science inquiry skills overview Biological sciences Questioning and predicting

PAGES

Planning and conducting

Processing and analysing data and information

Evaluating

Communicating

2–5 6–9 10–13 —

18–21

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22–25

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26–29

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30–33

38–41 42–45

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46–49

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50–53

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Questioning and predicting

54–57

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58–61 62–65

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Chemical sciences Planning and conducting

Processing and analysing data and information

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34–37

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14–17

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Communicating

66–69 70–73

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Science inquiry skills overview Earth and space sciences PAGES

Questioning and predicting

74–77

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78–81

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Planning and conducting

Processing and analysing data and information

Evaluating

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82–85

90–93

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102–105

110–113 114–117

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Physical sciences

122–125

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Questioning and predicting

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126–129 130–133 134–137 138–141

Planning and conducting

Processing and analysing data and information

Evaluating

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106–109

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86–89

98–101

Communicating

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Experiment format Title Goal

Materials

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Procedure

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Results

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Conclusion

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Scientific method process Subject Question

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Background research

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Hypothesise

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Analyse data

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Test hypothesis

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Communicate results

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Investigation format Title (What am I investigating?)

Prediction (What do I expect to discover?)

Procedure

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Equipment

(What do I need? How do I use it?)

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(How am I going to set up the investigation?)

Reliability

(How will I ensure a fair test?)

Observations/Measurements (How will I record what I see and/or measure?)

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Analysis of results

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(What do my results show? How do they relate to my prediction?)

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Developing explanations (What do my results mean?)

Communicating

(How will I present my results?)

Reflecting on methods (How effective was my method for this investigation? How would I change the method to provide more meaningful data?)

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What is classification and why is it important?

Inquiry skills focus:

• Students should have access to the internet and other resources for researching characteristics of individual animals.

Using taxonomy to order information about life on Earth

• Use the prepared named picture cards to demonstrate how the animals move within the chart.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• As a fun activity before commencing the chart, ask the students to predict the animal which will appear at the bottom of each arm of the chart. Check after completion. • Students make their charts on A3-size plain paper using a landscape layout. As new subgroups are formed with each question, students should write down the animals in those groups until the final set of each branch is reached. The first question, ‘Lays eggs?’ is highlighted so students can see where to start.

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• Within the Linnean system of classification, there are seven main levels of classification. These are kingdom, phylum, class, order, family, genus and species. There is debate as to how many kingdoms there are. Some say five: animalia, plantae, fungi, protista and monera; others say six, dividing monera into bacteria and archaebacteria. That there is debate shows that taxonomy is a dynamic science which is refreshed as research presents new evidence to support or refute old ideas.

• The questions and yes–no boxes should also be included on their charts.

• All known living organisms have been placed into one of the five (or six) kingdoms of life. They are then continually subdivided by extracting those with similar features until the species level is reached. Each organism at this level is given a binomial name. The first part is the name of the genus to which it belongs. The second part is exclusive to the individual species.

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• Allow students to compare their charts and explain reasons for their choice of answer if there is any dispute. Allow them to correct mistakes by retracing steps and further research.

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Answers

1. identify, classify or group, name 2. To recognise similarities and relationships among organisms so that common ancestors can be identified 3. (a) Carl Linnaeus (b) 18th 4. (a) All organisms in the Linnean system are given a universally understood scientific name. (b) Latin and Greek (c) They follow a specific set of rules. 5. All known living things, including microorganisms 6. (a) So we can protect it and also know the dangers it presents; for example: poisonous plants. (b) It has allowed them to see organisms that are invisible to the naked eye. (c) Scientists know about organisms that cause diseases. They can work out how to fight them. Science as a Human Endeavour question Nature and development of science Teacher check Refer to websites such as <http://www.anbg.gov.au/biography/linnaeus. html> for assistance.

• Some useful websites include: − <http://www.kidsbiology.com/biology_basics/index.php > − <http://www.kidzone.ws/animals/scientific.htm> − <http://www.factmonster.com/science/biology/five-kingdoms. html> Preparation

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Biological sciences

Content focus:

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• Each student will need A3-size plain paper for the activity on page 5. Prepare a chart on A2 paper with room to add the names of the animals in each subgroup. Prepare labelled picture cards of each animal. Students will require access to the internet and other resources. The lessons

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• Discuss classification within students’ everyday lives. Sometimes, classification is clear cut; for example, all the students in the school can be grouped according to their gender and/or ages. At other times, the lines are blurred; for example, furniture and appliances at home are grouped according to the rooms in which they are used, but sometimes the same things are useful in more than one room.

Page 5 1. 4. 7. 10. 13. 16. 19. 22. 25. 28.

• As an example of a commonly-accepted system of classification, discuss the Dewey decimal used in libraries throughout the world. • The activity on page 5 is designed to demonstrate how organisms can be grouped according to their physical features and characteristics. The animal examples and questions asked are random but the process of reducing the number of animals in the group, by asking yes–no questions, is standard.

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octopus toad slug snake chicken otter squirrel dog zebra kangaroo

2. 5. 8. 11. 14. 17. 20. 23. 26.

seahorse frog turtle crocodile dugong hippopotamus monkey goat horse

3. 6. 9. 12. 15. 18. 21. 24. 27.

prawn snail crab penguin dolphin sloth lion deer rhinoceros

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What is classification and why is it important? – 1 • to group organisms according to similarities of physical features and characteristics • to name organisms according to how they are grouped • to identify and classify newly discovered organisms.

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The diversity of life on Earth is enormous. For us to recognise the similarities and relationships among the many millions of organisms that exist in our world, they need to be grouped in some logical way that can be universally understood.

In the 18th century, Carl Linnaeus, a Swedish botanist, developed a taxonomy for identifying, classifying and naming organisms. A modified version of the Linnean system of classification is still used across the globe today.

© R. I . C.Publ i cat i ons Scientists follow a specific set of rules to give each organism a scientific name that is derived or r ev i ewThis pu r pconfusion oses on l ywho •speak from either • the f Latin or Greek language. avoids among people

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different languages. For example, the name Panthera leo means exactly the same thing whether you speak English, Hebrew, Chinese or any other language—it is the scientific name for the lion.

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Since Linnaeus’ time, scientists have been able to add to the work he began, providing a database of all known living things. This now includes microscopic organisms that can only be seen with the aid of a microscope, as well as those we can see with the naked eye.

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The work of taxonomists is important as it supports the efforts of conservationists to protect Earth’s biodiversity. The more we know about life on Earth, the better placed we are to protect it or to protect ourselves from it.

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The names given to living things by using the Linnean taxonomy indicate similarities among the physical features and characteristics of different organisms. With this information, scientists can: • identify patterns in nature and consider how and why they have occurred and how they might change; for example, how food webs in different ecosystems work and how they are affected by the destruction of habitats • examine the relationships among living things; for example, finding ways to prevent the spread of bacteria that cause disease and how the effects of poisons from plants and venom from animals can be treated. Although millions of organisms have been identified, scientists believe that there are many millions more that have yet to be discovered. The study of taxonomy has not been consistent across the globe and scientists believe that many more organisms, especially insects and microorganisms, may exist in areas where the science is not widely established. R.I.C. Publications®

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Biological sciences

Taxonomy is the science of classification. It has three main functions:

What is classification and why is it important? – 2 Use the text on page 3 to complete the following.

2. Why is it necessary to classify living organisms?

3. (a)

4. (a)

(b)

(c)

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(b)

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Who developed the Linnean system of classification?

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In what century was it established?

Why can people who speak different languages all understand the Linnean system?

From which two languages are the scientific names derived?

5. Which living things are included in the Linnean system of classification?

(b)

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6. (a)

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Why do we need to know about life on Earth?

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Biological sciences

1. Taxonomy is a science related to living things. What three things do taxonomists do to living things?

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How has the microscope helped scientists discover more about the natural world?

Write a simple fact file on Carl Linnaeus, including his contribution to the development of biological classification. AUSTRALIAN CURRICULUM SCIENCE

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Classifying living things

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Males incubate eggs? 3. N 2.Y

Has many arms? N 1.Y Has claws? 16.Y 17. N

Has feet? 10. N Y

Can swim? 13.N 12.Y

Eats meat? N Y

25.Y

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Has a single horn? 27.Y 28. N Biological sciences

26. N

Has a mane? Has cloven hoofs? Eats acorns? 21.Y 22. N Y N 19.Y 20. N Has a beard? 23.Y 24. N Has a mane? N Y Has stripes?

Hangs upside down? N 18.Y

Spends a lot of time in trees? Y N

Spends a lot of time in water? N Y

Has wings? Y 11 .N

Has four legs? 8.Y 9.N

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Carries a shell? N Y

Is herbivorous? 14.Y 15. N

Lives exclusively in water? N Y

Has one foot? N Y

Carries a shell? 6.Y 7.N

Has warts on body? 4.Y 5. N

Undergoes metamorphosis? N Y

Lives exclusively in water? N Y

Lays eggs?

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chicken, crab, crocodile, deer, dog, dolphin, dugong, frog, goat, hippopotamus, horse, kangaroo, lion, monkey, octopus, otter, penguin, prawn, rhinoceros, seahorse, sloth, slug, snake, snail, squirrel, toad, turtle, zebra

To classify organisms, taxonomists ask a range of yes–no (Y/N) questions to determine where they fit in a classification system. Follow the sequence of questions to make up a chart that separates each animal into a set on its own. Use the list of animals in the box to write the answers underneath the numbers 1 to 28.

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How are living things classified?

Inquiry skills focus:

• Give students the opportunity to share their research and help each other to resolve any identification issues.

Main method of classification of plants Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

Answers Page 8 1. (a) animal (b) monera (c) plant (d) protista (e) fungi 2. (a) bryophytes (b) pteridophytes (c) gymnosperms (d) angiosperms 3. (a) Cycads have large waxy fronds, conifers have needles, ginkgos have needles that are joined together. (b) Leaves of monocot seed plants are simple, long strands. Leaves of dicot seed plants are complex and have veins. 4. (a) They all have a vascular system, which bryophytes do not. (b) They produce seeds, but pteridophytes produce spores. 5. Count the petals. Monocots are divisible by three. Dicots are divisible by five. 6. (a) They do not have a vascular system to transport water and nutrients up to tall parts of the plant. (b) They can be transported by the wind and animals to other locations where they can germinate.

• Plants are unique as their cell walls contain cellulose, which allows them to stand upright. They are categorised by the presence or absence of a vascular system and by seed structure and overall stature. • Non-vascular plants do not have true roots, stems and leaves. Most plants are vascular. The tubular stems which conduct water are called xylem.

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• Some useful websites include: − <http://www.biology4kids.com/files/plants_main.html> − <http://www.perspective.com/nature/plantae/index.html> − <http://homeschooling.gomilpitas.com/explore/botany. htm#Classifications>. Preparation

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• Taxonomy, the science of classification, allows scientists to study all living things in an organised way. Organisms are placed in one of the five (or six) kingdoms based on similarities among characteristics and features.

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Teacher check. Attention paid to detail in diagrams should be noted.

• Find and display pictures of each type of plant referred to in the text. Present them as in the classification tree on page 7.

The lessons

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• Acrylic glasses, water, food colouring, and celery stalks with leaves attached are required for the classroom demonstration.

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Biological sciences

Content focus:

• Explain any unfamiliar botanical terms from the text. Monocotyledon and dicotyledon are usually referred to as monocot and dicot, respectively. Monocotyledon (monocots) are a group of flowering plants which have only one cotyledon (leaf embryo) in the seed and an endogenous (growing or originating from itself) manner of growth. Dicots are plants with two cotyledons.

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• Demonstrate the vascular system of plants by standing celery stalks in coloured water. Students will observe the coloured water rising up the xylem in the stalks. These are clearly visible in celery. • Before completing the activity on page 9, encourage the students' prior knowledge. Ask them to predict what plants they will find in their immediate environment. • Students need access to the outside environment to complete the activity on page 9. They should pay close attention to detail in their diagrams. • After examining the plants in situ, students should find images on the internet with which to compare to and elaborate their drawings.

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In biological classification, all known living things are put into one of the five (sometimes six) biological classification kingdoms. Within a kingdom, organisms have many more differences than similarities. Determining the kingdom to which an organism belongs is based on broad similarities. An organism made up of many different types of cells is a metazoan. It can belong to: The plant kingdom

The animal kingdom

The fungi kingdom

Organisms make their own food and Organisms do not make their own are immobile. food but are mobile. Cell walls contain cellulose.

Organisms do not make their own food and are immobile.

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An organism with only one cell is a protozoan. It can belong to:

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The protista kingdom

The monera kingdom

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Organism has a nucleus (controlling part) within Organism does not have a nucleus within its its cell. cell.

There are well over 300 000 species in the plant kingdom. How can people begin to classify them? A major division between plants is those that do and those that do not have a vascular system. A vascular system is a method of transporting water and nutrients from the roots to the stems and leaves. It allows plants to grow tall. Another division is between the vascular plants that reproduce from seeds and those that reproduce from spores. Spores are produced on the underside of mature leaves of pteridophyte plants. Plants that produce seeds are further divided into angiosperms (flowering plants), in which the seeds are hidden inside an ovary within a flower, and gymnosperms (conifers), in which the seeds are easily visible. All plants Classification assigns organisms into groups from broad categories to specific. At the kingdom level, there are Has a vascular system? many thousands of organisms in one Yes No group. At the species level, there are many thousands of groups but only one species in each. Bryophytes mosses and worts: Very short. Form Reproduces by seed? 'carpets' on the ground. Need water to Angiosperms Yes No reproduce. Covered in tiny hairs. Live Flowering plants: Pollinated by the in dark, damp places. wind, insects and other animals.

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o c . che Seeds hidden? e r Pteridophytes o t r s ferns: Soft plants. Need water to super reproduce. Baby ferns called zygotes.

A cotyledon is the part of a hidden seed that protects the embryo, providing nourishment for the developing plant. Some plant seeds have one. Others have two or more. monocotyledon seeds: Petals formed in groups of three. Leaves are simple, long strands; e.g. grasses, cereals, palm trees and lilies. dicotyledon seeds: Petals formed in groups of four or five. Complex, veined leaves; e.g. roses, sunflowers, fruit trees and cacti. R.I.C. Publications®

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Yes

Gymnosperms cycads: Large cones in centre of plant. Large fronds have waxy coating. conifers: Leaves are pine needles. Cones on branches. ginkgos: Needles combine to form strong ‘leaves’. Resistant to pollution and attack by insects. 7

Large stems. Leaves are called fronds. horsetails: Tough, rough plants.

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Biological sciences

How are living things classified? – 1

How are living things classified? – 2 Use the text on page 7 to complete the following.

(a)

An active metazoan that relies on others to feed it

(b)

A protozoan without a controlling part

(c)

A metazoan that makes its own food but can not move around

(d)

A smart protozoan

(e)

A lazy metazoan

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2. Which plant group am I? (a)

I do not have a system for transporting water around me.

(b)

I have a vascular system. I make spores to reproduce.

(c)

I have a vascular system. My seeds can be easily seen.

(d)

I have a vascular system. My seeds are hidden.

3. (a)

How are the leaves of cycads, conifers and ginkgos different?

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How are the leaves of angiosperms with monoct seeds different from those with dicot seeds?

4. (a)

In what way are pteridophytes, gymnosperms and angiosperms similar to each other and different from bryophytes?

(b)

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(b)

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Biological sciences

1. Write the correct kingdom for each organism.

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In what way are gymnosperms and angiosperms similar to each other and different from pteridophytes?

5. How could you tell the difference between two angiosperms if one had seeds with one cotyledon and the other had seeds with two cotyledons?

6. (a)

(b)

Why do you think bryophytes are very short plants?

How do you think producing spores and seeds benefit the survival of plant species?

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Whether you live in a rural or an urban area, you are close to many species from the plant kingdom. You are going to classify some plants in your local area. You will need: • sharpened HB pencil

• magnifying glass

• plastic gloves.

1. Find three vascular plants that are as different from one another as possible. 2. Examine all their features very carefully by using the magnifying glass.

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3. Complete the table.

Plant 2

Plant 3

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Plant 1

Diagram of whole plant

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Diagram of seed or flower

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Diagram of leaf

Pteridophyte, gymnosperm or angiosperm R.I.C. Publications®

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AUSTRALIAN CURRICULUM SCIENCE

Biological sciences

Classifying local species

What are the hierarchical levels of taxonomy? How organisms are ranked within levels of classification

Inquiry skills focus:

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

• In Question 4, students compare if the organisms they have grouped together fall into the same groups in the Linnean system. Students should complete the table logically, putting all organisms in the same kingdom together, then following suit with phylum, class, order, family, genus and species. • Give students the opportunity to share their research and help each other to resolve any identification issues. Answers

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Background information

• While placement of organisms within the biological classification system is based on similarities of characteristics and features, common ancestry takes priority; for example, sharks and dolphins both have fins but dolphins give birth to and suckle live young so they are mammals. • A useful website is: − <http://www.kidsbiology.com/biology_basics/classification/ order_family_genus6.php>.

Phylum

Chordata

Class

Mammalia

Order

Carnivora

Family

Felidae

Genus

Felis

Species

Felis catus

• Prepare a chart to show the hierarchical classification of people in your school. The lessons

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• Use the prepared chart to help students understand a hierarchical system, considering all the people who spend their days at the school. They can be divided broadly into staff and students. Staff can be subdivided into teaching, administration and ancillary. Students can be subdivided into lower, middle and upper, then further into individual classes, then even further into boys and girls. The same process applies to the levels of biological classification. With each subdivision, the organisms/people in the group are more similar.

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Science as a Human Endeavour question Nature and development of science

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Preparation

1. (a) animalia, plantae, fungi, protista, monera (b) animalia, plantae and fungi because they can be seen without the aid of a microscope. 2. (a) True (b) True (c) False (d) True (e) False 3. (a) Snake: It is the only one with a backbone. (b) Penguin: It is the only one that is not a mammal. (c) Cheetah: It is the only one that does not belong to the Panthera genus. (d) Hyena: It is the only one that does not belong to the Canidae family. 4. Kingdom Animalia

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• The different levels of the Linnean classification system are hierarchical. This means that each level holds a rank in which the members also belong in the same group to the level(s) above, but not necessarily to the same group in the level(s) below.

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Biological sciences

Content focus:

Students could include Aristotle, Greek (384–322 BCE); John Ray, English (1627–1705); Carl Linnaeus, Swedish (1707–1778); Georges Cuvier, French (1769–1832); Ernst Haeckel, German (1834–1919); Edouard Chatton, French (1883–1947); Robert Whittaker, American (1920–1980); Carl Woese, American (1928–). The following website may be helpful: <http://www.biologyreference.com/Ta-Va/TaxonomyHistory-of.html>.

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• Before the activity on page 13, ask students to name different types of ocean life, including coral, sponges, jellyfish and crustacea as well as fish and mammals. This will help students with the timed activity. Students could predict how many ocean creatures they will be able to list before completing the timed activity.

Page 13

Teacher check. Table should be completed logically.

• Discuss the questions they can ask to classify their chosen species into different levels; for example, does it have a backbone, lay eggs, have fins? Their methods of classification are not incorrect as they are classifying based on their own criteria. Recognising how many different methods there can be within the class will help them to understand why it is useful to have a standard system that everyone uses.

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All known living things have been identified and arranged in a system that groups organisms with similar physical features and characteristics together. This shows the diversity of life on Earth and the evolutionary relationships among living things. The Linnean system of classification is a hierarchical system. Organisms are classified broadly into kingdoms; then, with each subdivision of groups within levels, the differences among organisms are reduced until the level of individual species is reached. Although there may be differences in the appearance of organisms within a species, they are capable of mating and producing fertile young.

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The five kingdoms of life are: animalia, plantae and fungi, which can be seen with the naked eye; and protista and monera, which can be seen using a microscope.

Kingdom

Phylum

Class

Animalia

Arthropoda

Mollusca

Chordata

(insect, spider, shrimp)

(snail, squid, clam, mussel)

(animals with a backbone)

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Teac he r

Follow the example that shows the classification of some species of the cat family.

Annelida

(segmented worm)

Mammalia Reptilia Amphibia AvesR © . I . C . P u b l i c a t i o n s (suckle young, hair (all birds) (lizard, snake) (frog, toad, newt) on body) •f orr evi ew pur posesonl y• Perissodactyla (horse, rhinoceros)

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Order

Proboscidea (elephant)

Artiodactyla (sheep, deer, giraffe)

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Family

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Chiroptera (bat)

Rodentia (rat, mouse)

Primates (monkey, human)

o c . che e r o (dog, fox, wolf, jackal) t r sFelidae super (giant panda, polar, grizzly)

Carnivora (cat, stoat, weasel)

Insectivora (mole, shrew)

Hyaenidae (hyena)

Canidae Ursidae

Genus Acinonyx

Species

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Panthera

Panthera onca (jaguar) Acinonyx jubatus Panthera leo (cheetah) (lion) www.ricpublications.com.au

Felis

Panthera tigris (tiger) Panthera pardus (leopard)

Uncia

Felis catus (domestic cat) Uncia uncia (snow leopard) AUSTRALIAN CURRICULUM SCIENCE

Biological sciences

What are the hierarchical levels of taxonomy? – 1

What are the hierarchical levels of taxonomy? – 2 Use the text on page 11 to complete the following.

(b)

What are the five kingdoms into which all life on Earth is classified in the Linnean system of classification?

Which three do you think would be the easiest to classify and why?

2. Tick True or False. (a)

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False

All zebras are mammals but not all mammals are zebras.

(b)

Ursidar is the name of the bear family.

(c)

Bats are reptiles.

(d)

Moles eat insects.

(e)

The leopard belongs to the same genus as the snow leopard.

3. Which is the odd one out and why?

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Teac he r

(b)

(c)

cheetah, jaguar, leopard, lion, tiger

(d)

dog, fox, hyena, jackal, wolf

(a)

shrimp, snake, snail, spider, squid

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Biological sciences

1. (a)

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4. Classify the domestic cat according to the seven levels of the Linnean system.

Read about the contributions of some key people to the development of biological classification. Record them in a time line and include their nationalities. AUSTRALIAN CURRICULUM SCIENCE

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There are countless species of life in our oceans, many of which are still unknown. Thanks to the efforts of scientists, writers and filmmakers, many of us are familiar with the many forms of ocean life. You are going to classify some examples of ocean life. You will need: • a stopwatch

• access to the internet and other resources

What to do

• pieces of card.

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1. On note paper, write the names of as many ocean-living types of organisms as you can think of in one minute.

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2. Write each name on a piece of card. Move the cards around as you decide how to classify the different species.

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3. Record your classification system.

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4. Research and record the Linnean taxonomy of each of your species.

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5. How does your classification system compare with the Linnean classification system?

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Biological sciences

Ocean life taxonomy

How has classification changed over time?

Inquiry skills focus:

Answers

How classification changed with the discovery of evolution

Page 16 1. (a) animal, vegetable, mineral (b) Mineral: Minerals are no longer classed as living things. 2. (a) By physical features; e.g. type of feet or leaves, numbers of petals, presence of horns; by characteristics; e.g. how they grew, breathed, moved. Students can add their own examples. (b) They are the same now as they always were and always will be. 3. (a) How different species can evolve and survive by adapting to changes in the environment. (b) Species that can adapt to changes and breed to produce young that can also adapt, will survive environmental change. (c) Different species that evolved in different ways over time because of changes to their environment have descended from the same species. 4. Mineral kingdom removed. Protista kingdom added to include microscopic plants and animals. Fungi kingdom added as fungi neither animal nor plant. Monera kingdom added with discovery of bacteria and later split into two separate kingdoms. Science as a Human Endeavour question Nature and development of science

Planning and conducting Processing and analysing data and information Communicating

Background information

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• Taxonomy classifies organisms into similar groups so that patterns in nature can be recognised. Both the Linnean system and modern cladistics are used. (Cladistics is based on common ancestry and the branching evolutionary tree. Groups into which organisms are shared are called clades. A cladogram shows the split from the evolutionary tree of each newly-evolved species.)

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• When Linnaeas produced his system, it fitted the beliefs of the day and was expected to one day be complete. But Darwin’s theory of evolution changed that. Classification is now an open-ended investigation that is subject to change, with developments in science that can support or refute the placing of an organism in a particular group. • Evolution is a very slow change that occurs in response to environmental changes. By studying fossils that have been unearthed, scientists have been able to gather evidence to support the theory of evolution. Usually, fossils clearly belong to a specific group but in the cases of the Tiktaalik and Ichthyostega (which were fish with legs), they show an evolutionary link between fish and amphibians.

Teacher check. Before Darwin, most people believed that living things were as they always had been and always would be. Darwin hypothesised that, over a long time, living things evolved to suit their environment and those which could not became extinct. Today, the effects of human activity over a short period of time has driven many living things to the brink of extinction because they have not had time to adapt.

• All species of otter belong to the Mustelidae family, which also includes badgers. Mustelids have long, sleek bodies with thick hair and scent glands on their tail.

Page 17

1. giant otter – Pteronura brasiliensis 2. (a) southern river otter (Lontra provocax); neotropical river otter (Lontra longicaudis) (b) oriental small-clawed otter (Aonyx cinerea): smooth-coated otter (Lutrogale perspicillata) 3. North American river otter (Lontra canadensis) sea otter (Enhydra lutris) spotted-necked otter (Hydrictis maculicollis)

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• Some useful websites include: − <http://www.christs.cam.ac.uk/darwin200/pages/index. php?page_id=j l> − <http://earlyhumans.mrdonn.org/evolution.html> − <http://anthro.palomar.edu/animal/animal_1.htm> − <http://www.visionlearning.com/library/module_viewer. php?mid=68> Preparation

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Content focus:

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• For the activity on page 17, collect pictures of all species of otter if possible and label with their scientific names. The lessons

• Emphasise that classification is not a natural process but a system designed by, and for the use of, people. Things of nature are not designed to fit neatly into tables or tree diagrams. Classification systems are merely ways to organise the knowledge we have of the natural world in a way that it may be accessible to all. • Unfamiliar scientific names may confuse some students. Encourage them to sound out the names and say them slowly. This will help them to write and spell them correctly and confidently.

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In 1735, a Swedish scientist, Carl Linnaeus produced a system for classifying all natural things in the world based on their physical features (for example, type of feet, presence of horns, type of leaf, number of petals) and characteristics, including how they perform the functions of life (for example, do creatures have lungs or gills for breathing?) Organisms were classified into one of three ‘kingdoms’—animal, vegetable or mineral—and then each was subdivided into different levels until each individual organism was named. Until the mid-19th century, scientists continued to classify organisms based only on observable features. The idea of evolution was unknown. They believed that all organisms existed as they had always done in the past and as they always would in the future.

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Charles Darwin’s book, On the origin of species by means of natural selection (1859), was to change the way scientists looked at the natural world. On his famous voyage aboard HMS Beagle, that took him to the volcanic Galápagos Islands in the Pacific Ocean, about 1000 km to the west of Ecuador, Darwin discovered proof of the theory of evolution by natural selection.

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Evolution means things change over time. Natural selection is the way these changes occur. Living things adapt to the changing conditions of their environment so they can survive and thrive. In the expression ‘survival of the fittest’, ‘fittest’ means the ability to mate and produce offspring. Organisms that can adapt and breed will continue to exist. They are fitter than organisms that can not adapt and struggle to survive. Darwin found that a type of finch (bird) that lived on the mainland of South America also lived on each of the Galápagos Islands. However, on each island the birds had different sized beaks. Darwin concluded that as the environment of each island was unique, the birds had adapted in order to survive. As birds that could adapt mated, they produced offspring that were also able to adapt. These birds became dominant in number and those that could not adapt eventually disappeared. From one single type of finch, many more evolved by natural selection.

© R. I . C.Publ i cat i ons Scientists who accepted Darwin’s theory of evolution believed that living things had changed over orr eand vi ewcontinue putor pos eso nthings l y• time to suit • theirf environment would change. Different living in the present day have had common ancestors, and the individual organisms of today will be the common ancestors of different organisms in the future.

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mangrove finch (Camarhynchus heliobates)

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Eats ma inly ins e

s seeds Cactu and parts

The science of taxonomy is constantly sharp-beaked ground finch (Geospiza difficilis) evolving—always dynamic and never static. Also, there are many living things on land and at sea that have yet to be discovered. R.I.C. Publications®

large tree finch (Camarhynchus psittacula)

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medium tree finch (Camarhynchus pauper)

Bud s&

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The Linnean classification system has also evolved as advances in sciences have provided evidence for scientists to either uphold or neglect small tree finch (Camarhynchus parvulus) previously held beliefs. For example, minerals have been removed from the system, which now focuses solely on living things. With the advent of the microscope in the vegetarian finch middle of the 18th century, protists (Camarchynchus crassirostris) were added to include all singlecelled microscopic plants and animals. Further studies in the new field of microbiology led to the discovery of bacteria, for which large cactus finch (Geospiza conirostris) a new kingdom (monera) was established. It was later recognised that fungi are neither animal nor cactus finch plant, but belong to a kingdom of (Geospiza scandens) their own.

woodpecker finch (Camarhynchus pallidus)

ancestrial seed-eating ground finch

warbler finch (Certhidea olivacea)

d E ats m ainly s e e

Cocos Island finch (Pinaroloxia inornata)

small ground finch (Geospiza fuliginosa)

medium ground finch (Geospiza fortis) large ground finch (Geospiza magnirostris)

AUSTRALIAN CURRICULUM SCIENCE

Biological sciences

How has classification changed over time? – 1

How has classification changed over time? – 2 Use the text on page 15 to complete the following. When Linnaeus first produced his system of classification, what were the kingdoms of life among which all living things were divided?

(b)

One of these kingdoms is no longer present in biological classification. Which one and why does it no longer exist?

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2. Before Charles Darwin developed the theory of evolution: (a)

how did scientists decide how to classify living things? (Give examples.)

(b)

3. (a)

what were scientists’ beliefs about the existence of living things?

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What do you think Charles Darwin explains in his book, On the origin of species by means of natural selection?

(c)

According to Darwin, how can different species have common ancestors?

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(b)

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Biological sciences

1. (a)

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4. List the ways in which today’s biological classification system is different from the original system.

How did Darwin’s theory of evolution change how people thought about the natural world? Why have some living things not been able to adapt to the effects of human activity on the environment? AUSTRALIAN CURRICULUM SCIENCE

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The Linnean system of classification proved to be extremely useful in its day but as ideas changed, evolutionary relationships became important and the system of cladistics was introduced. Cladistics classifies organisms into groups called clades. Each clade consists of an ancestor organism and all of its descendants. Each clade is a branch on the ‘tree of life’. Over time, organisms within a clade evolve as they adapt to changes in their environment. This cladogram shows how the 12 present-day species of otter in the world have evolved over time. Each node identifies a point in time when the otters split from the main clade.

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Study the cladogram and answer the questions, using the common and scientific names.

Lutrinae (otter)

North American river otter (Lontra canadensis) marine otter (Lontra felina)

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giant otter (Pteronura brasiliensis)

southern river otter (Lontra provocax)

neotropical river otter (Lontra longicaudis) Node 1

sea otter (Enhydra lutris) Node 2

spotted-necked otter (Hydrictis maculicollis) Eurasian otter (Lutra lutra)

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smooth-coated otter (Aonyx capensis) 1. At Node 1, which single species of otter split from the main clade?

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2. Write the two closest relatives to each otter. (a) Marine otter (Lontra felina)

(b) African clawless otter (Aonyx capensis)

3. After the clade split at Node 2, which three single, and separate species evolved?

4. Research to present a cladogram for another animal with a small number of different species; for example: penguin, whale. Draw the cladogram on the back of this sheet. R.I.C. Publications®

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Biological sciences

The tree of life

How are living things named?

Inquiry skills focus:

3. (a)

Binomial nomenclature and how names are derived

Horse Dog Goat

Planning and conducting Processing and analysing data and information Communicating

Background information

Teacher check. Diagrams should be detailed and labelled and include common and scientific names.

• Collect pictures of different species of the same genus of an animal, plant and fungus. Prepare scientific name labels to attach to them.

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• Look at the pictures of species of animal, plant and fungus. They belong to the same genus but have differences as well as similarities. Discuss these. Attach the labels to each picture to show the names of each species. Does the name suggest anything about the organism's features, habitat or location? It might be named after a person (which would not be evident).

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• For the activity on page 21, students will need to work outside. The ecosystems they choose can range from a manicured flowerbed to an untended weedy patch of soil. The more diverse the plots the better, as this will demonstrate that ecosystems can exist anywhere.

Page 20

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Page 21

Preparation

Answers

Species Subspecies ferus caballus lupis familiaris aegagrus hircus

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• Some useful websites include: − <http://www.scientificname.net/> − <http://www.nhm.ac.uk/nature-online/science-of-naturalhistory/taxonomy-systematics/history-taxonomy/session1/index. html>.

The lessons

Genus Equus Canis Capra

(b) (i) E. f. caballus (ii) C. l. familiaris (iii) C. a. hircus 4. Teacher check. The correct genus name must be given in all cases. Horse – Equus, dog – Canis, tiger – Panthera Science as a Human Endeavour question Nature and development of science Teacher check. Information about DNA can be found at <http://www. neok12.com/Genetics.htm> and the electron microscope at <http:// encyclopedia.kids.net.au/page/el/Electron_microscopy> and <http:// school.discoveryeducation.com/lessonplans/interact/vemwindow.html>.

• In the 19th century, rules were established to govern how newly discovered organisms would be named. The name of a genus and species can be derived from any source but it is always given a Latin spelling. In biological classification, binomial nomenclature is officially recognised and used, taking the name of the genus and the specific name to give the name of the individual species.

Teac he r

Biological sciences

Content focus:

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1. (a) It identifies an organism within a classification system. Everyone understands exactly which organism is being identified. Language is not a barrier. (b) Some common names are only known in some places. An organism might have more than one common name. The same common name can be used for more than one organism. 2. (a) The genus and the species. The genus always begins with a capital letter but the species name never does. The genus and species names are either written in italics or are underlined. (b) (i) Panthera leo persica or Panthera leo persica (ii) Panthera tigris altaica or Panthera tigris altaica (c) It may be named after a person or after a characteristic or feature of the organism. (d) when a species is split into subspecies AUSTRALIAN CURRICULUM SCIENCE

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How are living things named? – 1 Its scientific name is unique and universally understood. It identifies an organism in its place within biological classification. All living things have only one scientific name. For example, only one species is named Fuligo septica. People discussing this species know for certain that they are talking about exactly the same thing. Its common name may vary in different parts of the country or in other parts of the world. For example, the slime mould Fuligo septica is commonly known as ‘dog vomit slime’ and ‘scrambled egg slime’. It is also possible that different organisms may share a common name. For example, the plants Gypsophila muralis, Gypsophila paniculata and Gypsophila elegans are all called ‘baby’s breath’.

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The scientific naming of organisms was introduced in the mid-18th century when the Linnean system of classification was established. Since then, all living things have been given a binomial (or two-part) scientific name.

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The Latin language has always been used for scientific naming as it was the language used by academics at the time. Today, there are rules that must be followed when naming species. They are governed by the International code of zoological nomenclature (for animals) and International code of botanical nomenclature (for plants). The first part of the scientific name denotes the genus to which the species belongs. For example, the scientific name for a human is Homo sapiens. Homo is the name of the genus. A genus contains a number of species that are more closely related to each other than to other species.

The second, unique part of the name can be determined by a particular characteristic of the species or after a person: e.g. in Homo sapiens, sapiens means 'wise'. Agathidium vaderi, a recently identified slime mould beetle, has been named after the Star wars villain Darth Vader because both have broad shiny heads and similar eyes!

Panthera

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Genus leo

Species

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The species is usually the final level of classification, but in some cases the species is split into subspecies. These are given trinomial names.

tigris

leo (Barbary lion)

tigris (Bengal tiger)

persica (Asiatic lion)

sumatrae (Sumatran tiger)

krugeri (South African lion)

altaica (Siberian tiger)

o c . che e r o t r s super The genus name is always written with a capital letter but the species name uses lower case. Both the genus and species name are usually written in italics; or if not, they are underlined. After the full name has been written once, the abbreviated form can then be used within the same text. For example, the name for lion can be written as P. leo and South African lion as P. l. krugeri.

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Biological sciences

Every known living thing has two types of name.

How are living things named? – 2 Use the text on page 19 to complete the following.

(b)

2. (a)

What are the advantages of having scientific names for all living things?

What are the disadvantages of the common names of living things?

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(b)

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Which levels of taxonomy are used in scientific naming and how are they written?

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Using both acceptable forms, write the full names of the:

(i) Asiatic lion. (ii) Siberian tiger.

(c)

(d) 3. (a)

How is the species name decided?

© R. I . C.Publ i cat i ons When is a trinomial name given? •f orr evi ew pur posesonl y• Complete the table for: the horse – Equus ferus caballus, the dog – Canis lupus familiaris and the goat – Capra aegagrus hircus Genus

Species

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Horse Dog

Goat (b)

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Write the abbreviated form of each scientific name. (i) horse

Subspecies

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Biological sciences

1. (a)

(ii) dog

(iii) goat

4. Suggest names for a new subspecies of each animal. They must reflect something about the appearance, character or location. To make the names sound Latin, add -a, -us or -um to the ending; for example: Canis cutius melbournia (the cute dog from Melbourne). Genus

Species

Subspecies

Meaning of name

horse dog tiger A scientific name is unique to a species but this name may change as modern technology provides ways to examine organisms more closely. Examples include DNA testing and the electron microscope. Find out more about these methods. AUSTRALIAN CURRICULUM SCIENCE

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In your local environment, there may be a number of ecosystems; for example: a small pond, a wildflower garden or a vegetable patch. There you will find many examples of plant, animal and fungus species. You will most probably know the common names of many species but not their scientific names. Here is your chance to learn a little bit of Latin or maybe Greek ... You will need: • specimen jar with lid, punctured with air holes • magnifying glass What to do

• sharpened HB pencil and eraser

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• garden trowel

• plastic gloves

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1. Find an ecosystem to investigate. Wear gloves to examine the physical appearance of three individual species you find there (examples each of animals, plants and fungi, if present). It may be necessary to dig the soil lightly to unearth some animals. These can be examined one at a time in the specimen jar or on the plastic tray. 2. Make a detailed, labelled drawing of each specimen and write its common name.

3. Find a picture and information about each specimen on the internet. Does your specimen have any other common names? 4. Write the scientific name for each specimen and add labels to complete your diagrams. Common name(s)

Specimen

Scientific name

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Biological sciences

Scientific names of local species

How are unknown organisms identified? 3. (a) (i) Oak: branches arranged alternately, leaves simple and lobed (ii) Hawthorn: thorned branches arranged alternately, leaves simple (iii) Birch: branches arranged alternately, leaves simple (iv) Walnut: branches arranged alternately, leaves compound, twig pith plated (v) Elder: branches opposite each other, compound leaves (b) They both have opposite branching and simple leaves. The leaves of the sugar maple have a smooth outline. Those of the red maple have a toothed outline. 4. Branches arranged alternately?

Using and creating a dichotomous key

Inquiry skills focus: Planning and conducting Processing and analysing data and information Evaluating Communicating Background information

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• The word ‘dichotomous’ means ‘divided into two parts’. In a dichotomous key, by asking a series of yes–no answer questions a group of things is constantly divided into two parts, adding numerous branches to the key … until, eventually, individual things are identified.

Leaves simple?

Yes

• Dichotomous keys are used to identify unknown specimens or to separate a group of specimens based on specific characteristics. In the latter, those with similar characteristics can be identified.

Leaves lobed?

Twig pith plated?

Yes

Oak

• Dichotomous keys have been used extensively in biological classification but they do have limitations. For example, if an unknown specimen does not display any characteristics stated in a key, it can not be identified by that key.

Walnut

Tree has thorns?

• A useful website is < http://www.penguinworld.com/index.php>. Preparation

Yes

Hawthorn

Birch

Ash

Leaves simple? No

Yes

Elder

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Leaves have smooth outline? Yes

Sugar maple

Red maple

Science as a Human Endeavour question Nature and development of science

Teacher check. Examples could include production of fertilisers in agriculture and horticulture, the use of yeasts and moulds in the food industry, and the production of medicines and vaccines in medical research.

• Pieces of card and pictures of each insect for students to make labelled insect cards will be needed. Students will require a large sheet of paper to lay out their cards and write their questions.

Page 25

The lessons

1.–2. Teacher check 3. Students will present their diagrammatic keys on sheets of large paper. 4.–5. Teacher check Possible example: 1. Does it have wings? If yes, go to 2. If no, go to 8. 2. Does it have two pairs of wings? If yes; go to 3. If no, go to 7. 3. Does it have membranous wings? If yes, go to 4. If no, go to 5. 4. Does it have a narrow waist? If yes, it is a wasp. If no, it is a bee. 5. Does it have wings with scales? If yes, go to 6. If no, it is a beetle. 6. Are its front and back wings linked? If yes, it is a moth. If no, it is a butterfly. 7. Does it have caudal cerci? If yes, it is a fly. If no, it is a mosquito. 8. Does it have caudal cerci? If yes, it is a silverfish. If no, go to 9. 9. Does it have a narrow waist? If yes, it is an ant. If no, it is a flea.

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• For the activity on page 25, work through an example of creating a dichotomous key using familiar objects; for example, the contents of a pencil case: a pencil, eraser, ruler, pen, scissors. Encourage students to suggest yes–no questions to ask.

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Content focus:

• Students use the insect cards to create an adjustable dichotomous key diagram before committing it to paper. To start, asking the question, ‘Does it have wings?’ creates a logical division between the group of insects. They should continue with one branch of the diagram until an insect is identified before looking at other branches. On this key, questions do not need to be numbered.

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• Once the order of questioning is established and all insects have been identified, students can present their keys as a list of questions. In this format, the questions will have to be numbered so that the next step in the instructions can be given. Answers Page 24

1. How it performs its natural functions, how it adapts to the seasons and other environmental changes, and how it interacts with other living things. 2. A series of questions are asked to which the answers are either yes or no. After a number of questions, individual organisms are identified.

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In the early days of biological sciences, identifying an individual living thing was a long process. Its physical features had to be examined and recorded in detail and by hand. It had to be observed over time to see how it: • performed life’s natural functions such as growing and reproducing • adapted to the seasons and other environmental changes • reacted to other organisms in the environment. However, thanks to the efforts of early scientists and advances in science and technology, the task is much simpler today. There now exists a massive database of all known living things, classified in a way that is universally understood and generally accepted. This vast bank of knowledge allows researchers to identify unfamiliar or previously unknown organisms.

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By asking questions about an organism to which there is only a yes or no response, scientists can discover where the organism fits into the classification system and at which species level, so as to identify it and give it a scientific name. It can also be used by you, allowing you to identify organisms in your environment. This type of questioning is called a dichotomous (two-part) key. Depending on the answer, yes or no, the researcher is taken on a certain path through levels of classification until the organism is identified. The questions can be presented as either a list or a flow diagram. Before using a dichotomous key, a researcher needs to have some knowledge about the features of the type of organism he or she is investigating. Follow this dichotomous key to understand how some deciduous trees can be identified.

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opposite branching

alternate branching

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1. Are the branches arranged alternately? If yes, go to Q.2. If no, go to Q.6. 2. Are the leaves simple? If yes, go to Q.3. If no, go to Q.5. 3. Are the leaves lobed? If yes, the tree is an oak. If no, go to Q.4. 4. Does the tree have thorns? If yes, the tree is a hawthorn. If no, the tree is a birch. 5. Is the twig pith plated? If yes, the tree is a walnut. If no, the tree is an ash. 6. Are the leaves simple? If yes, go to Q.7. If no, the tree is an elder. 7. Do the leaves have a smooth outline? If yes, the tree is a sugar maple. If no, the tree is a red maple.

simple leaf

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smooth outline lobed leaf

toothed outline

non-lobed leaf pith of twig – plated

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compound leaf

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pith of twig – not plated

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How are unknown organisms identified? – 1

How are unknown organisms identified? – 2 1. What information needs to be collected before an organism can be identified?

2. How does a dichotomous key work?

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Write a brief description of each tree based on the information in the dichotomous key.

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3. (a)

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(i) Oak

(ii) Hawthorn (iii) Birch

(iv) Walnut

(b)

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4. Show the dichotomous key as a flow diagram.

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Use the text on page 23 to complete the following.

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In what industries do you think it might be important to identify different plant and animal species? Give reasons for your suggestions. AUSTRALIAN CURRICULUM SCIENCE

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Using a dichotomous key is simple, but creating one is a little more complicated. You need to know about the features of different organisms to be able to ask suitable questions. 1. Read the notes describing some of the features of each insect. Wings

Abdomen

no wings

no tail-like projections (caudal cerci) on tip of abdomen; narrow waist

two pairs of light, transparent (membranous) wings; the back wings hooked to the front

round body with no waist

ant

bee

two pairs of wings; back wings hidden under hardened front wings

butterfly

two pairs of wings covered in scales; wings not linked together

flea

no wings

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flattened, round body

one pair membranous wings no caudal © Rof. I . C.Pu bl i cat i o nscerci on tip of abdomen or ev ew pu r posesonl y• oner pair ofi membranous wings mosquito•f fly

two pairs of wings covered in scales; wings linked together

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moth

no wings

long caudal cerci on tip of abdomen

wasp

two pairs of membranous wings; back wings hooked to the front wings

slender body with narrow waist

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silverfish

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2. Glue a picture of each insect onto a small piece of card, then label.

3. On a large sheet of paper, use the insect cards you have made and devise a dichotomous key diagram by writing questions requiring ‘yes–no’ answers. Make sure the question will separate the insects into smaller groups until individuals are identified. Glue each insect card in place on your diagram. •

Begin with the question, ‘Does it have wings?’

•

Record the path of each insect through the diagram by writing its name at either the ‘yes’ or the ‘no’ side of each question.

4. On the back of this page, write your key as a list (as shown on page 23). 5. Compare your key to others in your class. R.I.C. Publications®

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Create a dichotomous key to identify insects

How do food chains show relationships in a habitat?

Inquiry skills focus:

The lessons

Food chains show the flow of energy in an ecosystem or habitat/Food chains show the relationships among predators and prey in a food chain

• Allow the students to read the text on page 27 independently, assisting with vocabulary as needed. Discuss the text and concepts presented when the students have finished reading. • The students should use the back of the worksheet if extra room is needed to answer the questions on page 28.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• For the activity on page 29, a very simple method of creating a mobile can be found at <http://www.rspb.org.uk/youth/ makeanddo/activities/foodchainmobile.asp?mode=adults>. Download page 9 'Experiment with nature' at < http://www. naturesweb.ie/Trialissue.htm>. This page has an image of another simple format of a coathanger food chain mobile which the students might find useful. Since this activity involves using the representation in conjunction with an oral presentation, time needs to be allocated for this. Answers

• Boiling-hot deep-sea geothermal vents are also considered primary sources of energy like the sun.

Page 28

• The arrows in a food chain can be translated as ‘is eaten by’. This may assist the students to remember the order correctly.

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• A food chain is an example of a system—a structure defined by its parts and processes.

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1. A primary source (such as the sun) provides energy for a primary producer (such as a plant, like grass) which is eaten by a primary consumer (such as a grasshopper). 2. Quaternary consumers eat tertiary consumers, who in turn eat secondary consumers. An example of a quaternary consumer is a polar bear or white shark. An example of a tertiary consumer is a bear. An example of a secondary consumer is a fox. NOTE: The examples given in the text do not necessarily belong to the same specific food chain. 3. An autotroph makes its own food while a heterotroph must depend on others for its food. All consumers (heterorophs) in an ecosystem rely on autotrophs for their food. 4. detrivores, decomposers 5. (a) whale – quaternary consumer (b) phytoplankton – primary consumer (c) seal – tertiary consumer (d) herring – secondary consumer (e) zooplankton – primary producer; (f) water flea – primary consumer (g) bass – tertiary consumer (h) algae – primary consumer (i) crayfish – secondary consumer (j) kingfisher – quaternary consumer 6. autotroph or heterotroph; herbivore or carnivore or omnivore

• A food chain almost always commences with plant life and concludes with an animal. • Some consumers may change positions in the food chain depending on their diet, for example, squirrels may eat acorns and fruit or insects and bird eggs. This changes its classification from primary consumer to secondary consumer. Humans can be considered both primary and secondary consumers since they are omnivores too.

• Visit <http://www.vtaide.com/png/foodchains.htm> to create an online food chain. An excellent source of basic information can be found at <http://www.crickweb.co.uk/ks2science. html#foodchains>.

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Content focus:

Preparation

• Students should be familiar with a number of different plants and animals before attempting this set of pages. They should also understand the terms ‘predator’ and ‘prey’.

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• Access to a dictionary might prove useful for students who wish to look up the meaning of specific words in the text on page 27.

Page 29

Teacher check

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All living things need energy to live. A food chain shows one path of the flow of energy and nutrients (or food) within an ecosystem or habitat. Effectively, a food chain shows the relationships between predators and prey. The primary source of energy for all living things on Earth is the sun. Plants absorb energy from the sun which they convert to chemical energy through a process called photosynthesis. They also take in nutrients, which contain energy, from the soil and use them to produce leaves, flowers and fruit. This is the beginning of energy conversion. Plants are primary producers (autotrophs) because they make their own food. All the species in an ecosystem or habitat depend on autotrophs.

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Primary producers are consumed. All consumers, because they can not make their own food and must depend on others for energy, are called heterotrophs. There are different levels of consumers and ways of classifying them. Consumers are most commonly classified by the food they eat.

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Primary consumers are herbivores (such as grasshoppers and rabbits) and eat the plants. They must obtain all the energy they require from consuming plants. Secondary consumers are carnivorous animals (meat eaters) that eat primary consumers (herbivores). A fox, for example, will consume a rabbit. Omnivores eat both plants and animals and also fit into this group. Tertiary consumers are carnivores that eat other carnivores. A bear, for example, will eat a fox. Some scientists also include another group, called quaternary consumers, in the food chain. This group consists of larger carnivorous animals which eat smaller carnivores. Examples of quaternary consumers are the white shark and polar bear. The top predators, or consumers, in a food chain usually have few or no natural enemies. When an animal in a food chain dies, it may be eaten by detrivores (animals such as vultures, crows, beetles or crabs) and then broken down by decomposers such as dung beetles, bacteria and fungi. Decomposers speed up the decaying process and release nutrients back into the soil for plants to use. The process of energy transfer then continues.

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TERTIARY CONSUMER (carnivore)

(heterotroph) QUATERNARY CONSUMER

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SECONDARY CONSUMER (carnivore or omnivore)

(heterotroph)

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(carnivore)

PRIMARY PRODUCER (autotroph)

(herbivore)

DECOMPOSER

DETRIVORE

(heterotroph)

(decomposer) (heterotroph)

(heterotroph)

The levels of a food chain, called trophic levels, tell the position an organism holds in the food chain. The arrows in a food chain are drawn from food source to food consumer. The amount of energy transferred along a food chain decreases with each level. R.I.C. Publications®

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How do food chains show relationships in a habitat? – 1

How do food chains show relationships in a habitat? – 2 1. What is the difference between a primary source of energy, a primary producer and a primary consumer? Give one example of each from the text in your explanation.

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2. What is the relationship between secondary, tertiary and quaternary consumers in a food chain? Give an example of each.

3. Explain the difference between an autotroph and a heterotroph.

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4. Which two words describe the final group of organisms in a food chain responsible for speeding up the decaying process? •

•

5. Classify the following organisms, which belong in marine habitats, according to their position in the food chain. Use the words in the box.

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primary producer

primary consumer

tertiary consumer

(a) whale

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(b) phytoplankton (c) seal (d) herring

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Use the text on page 27 to complete the following.

secondary consumer

quaternary consumer

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water flea

(g) bass

(h) algae

(e) zooplankton

(i)

crayfish

(j)

kingfisher

6. Suggest two ways organisms in a food chain could be classified other than as primary producers or primary, secondary, tertiary or quaternary consumers. • auto

•

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or omnivore

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Food chains are usually represented as diagrams, but the same information can be presented in other ways. Complete the steps below to create your own unique representation of a food chain. 1. Investigate different images of food chains by using an internet search and list one or two websites with possible ideas below.

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2. Select the manner in which you will present your information. Choose from the following:

• mobile

• cartoon strip

• piece of artwork

• soft sculpture

• other

• paper chain

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• 3-D model

3. Write the name of the habitat or ecosystem you will be representing.

4. List the different components of your food chain. (You do not need to include the sun or detrivores or composers, BUT you must include the links below.)

Primary consumer

Secondary consumer

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5. List the materials you will need to complete your food chain.

6. Make your food chain representation and present it to the class to explain how a food chain works.

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7. Evaluate your presentation (using the rating scale provided) in regards to: (a)

your oral presentation. Poor

(b)

Average

Good

Very good

Excellent

how effective your food chain representation proved as an aid to your oral presentation. Poor

Average

Good

Very good

Excellent

8. In small groups, as individuals, or as a class, vote for the best representation that accompanied an oral presentation. Tally the results and decide why the winning representation was the best. R.I.C. Publications®

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Food chain representation

What are food webs and what do they show?

Inquiry skills focus:

• When completing the information for the platypus sanctuary on page 33, the students will come across some organisms which they may not be familiar with. If queries arise while completing this activity, the following information may be useful: macrophytes are microscopic aquatic plants; detritus is debris such as that formed from the decay of organisms; a water boatman is an aquatic insect that paddles along the water surface with oar-like hind legs; and a backswimmer is another aquatic insect that acquired its name because it swims upside down, usually near the surface of the water.

Food webs are a complex network of food chains showing the flow of energy among different species in an ecosystem. Planning and conducting Processing and analysing data and information Communicating

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Background information

Page 32

• This set of pages should be completed after pages 26–29.

• Visit <http://www.vtaide.com/png/foodchains.htm> to see how interconnected food chains form food webs and <http://teacher. scholastic.com/activities/explorer/ecosystems/be_an_explorer/ map/form.htm#> to make a food web. The website <http://www. gould.edu.au/foodwebs/kids_web.htm> also includes a number of different habitats and food webs to create.

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1. A food chain shows the movement of food energy along one specific pathway and the relationship between a predator and its prey. A food web shows how a number of different plants and animals in an ecosystem are connected. A food web is a complex arrangement of food chains. 2. Teacher check 3. (a) single (b) more than one (c) complex 4. (a) trophic (b) producers (c) secondary (d) top (e) decomposers (f) autotrophs (g) heterotrophs (h) energy

• Knowledge about food webs assist scientists to organise the complex network of relationships among organisms. It helps them work out how to maintain species diversity and ecological stability.

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Page 33

• An ecosystem is a community of organisms that interact with one another and with the environment in which they live. Examples of environments include a pond or a rainforest.

Antarctic food web

• The trophic levels can also be represented as shown below. This arrangement includes omnivores.

killer whale

crabeater seal

S ER

Preparation

Platypus sanctuary food web platypus

seabirds

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southern pygmy perch

• Students can be introduced to the topic by viewing <http://www.bbc. co.uk/nature/blueplanet/webs/flash/main_game.shtml>, which uses the Great Barrier Reef as an example of a food web.

water flea

mayfly larvae

algae and macrophytes

The lessons • Allow the students to read the text on page 31 independently, assisting with vocabulary as needed. Discuss the text and concepts presented when the students have finished reading.

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small fish and squid

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PRODUCERS

phytoplankton

HERBIVORES

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OMNIVORES

Weddell and Ross seals

emperor penguin

Adélie penguin

krill

CARNIVORES

leopard seal

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Content focus:

dragonfly larvae

freshwater shrimp

freshwater snail

detritus

diving beetle larvae

water boatman

bacteria

2. Teacher check

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Food chains show the movement of food energy along one specific pathway and the relationship between a single predator and its prey. Food chain example: nuts mice wolves bears primary producer primary consumer secondary consumer tertiary consumer In reality, one species feeds on more than one food source, which in turn probably feeds on more than one food source. Most animals belong to more than one food chain and consume more than one kind of food to supply their energy needs. This complex arrangement of food chains is called a food web. Food webs show how a number of different plants and animals are connected within an ecosystem.

Food web example:

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snake

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dragonfly

hawk

rabbit trout

grass

fox

human

bacteria

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A food web is a series of organisms related by predator–prey activities; or a series of interrelated food chains. The levels of a food chain, called trophic levels, tell the position an organism holds. Those organisms which occupy the same position within a food chain make up the same trophic level in a food web. All the plants in a food web make up the first or ‘primary producer’ tropic level. All the herbivores comprise the second or ‘primary consumer’ trophic level and the carnivores that eat herbivores make up the third or ‘secondary consumer’ trophic level. The top levels (which include carnivores that eat other carnivores) comprise the tertiary and quaternary trophic levels. Detrivores and decomposers are found at both extremes since they breakdown dead organisms and return energy to the soil for plants to consume.

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AUT OTR OPH S

In any food web, energy is transferred from one level to another. During each transfer, energy is lost as each organism is consumed, which decreases until it reaches the top predators in the food web. Often energy transfer is represented as a pyramid, with a large number of primary producers (plants) at the bottom and a small number of tertiary or quaternary consumers at the top.

HET ERO TRO PHS

The levels can also be grouped as autotrophs (organisms/ plants that manufacture their own food) and heterotrophs (that must depend on other organisms for their food energy).

QUATERNARY CONSUMERS TERTIARY CONSUMERS

SECONDARY CONSUMERS

PRIMARY CONSUMERS

PRIMARY PRODUCERS

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What are food webs and what do they show? – 1

What are food webs and what do they show? – 2 Use the text on page 31 to complete the following.

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2. Write a definition of a food web in your own words.

3. Select the most appropriate words. single

(a) Consumers in a food chain eat

multiple

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food sources.

(b) Most organisms belong to

only one

more than one food chain.

4. Complete the words missing from the cloze. The levels of a food chain which show the position an organism holds are called

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1. What is the difference between a food chain and a food web?

levels. The organisms in the same trophic level of a food chain

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occupy the same level in a food web.

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The first trophic level is occupied by the primary is occupied by the

The who are carnivores too.

. The second level

consumers, who are carnivores.

levels are occupied by the tertiary and quaternary consumers,

Detrivores and

are found at both extremes of the food web pyramid. f

The first level can also be labelled

and the remaining levels labelled

. h

The trophic levels show the transfer of

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from one level to another.

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1. Use the following websites and the blank formats to complete two food webs. Label each ellipse to represent each organism and include arrows to show the transfer of energy.

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Antarctic food web: refer to <http://amurdoch.tripod.com/yr4/fauna.html>.

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2. Select and research a land-based habitat to complete a food web of your own on a separate sheet of paper.

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Construct a food web

What else do food webs show?

Inquiry skills focus:

The lessons

Food webs may be represented as an energy pyramid/Food webs show the balance of nature.

• Allow the students to read the text on page 35 independently, assisting with vocabulary as needed. Discuss the text and concepts presented when the students have finished reading.

Planning and conducting Processing and analysing data and information Evaluating Communicating

• The students should use the back of the worksheet if extra room is needed to answer Questions 1, 2, 4 and 5 on page 36. • Page 37 involves students viewing and evaluating two different representations of an energy pyramid, then selecting a format of their own to construct. These can be either 2-D or 3-D representations.

r o e t s Bo r e p ok u S Answers

Background information

Page 36

• In 1927, animal ecologist Charles Elton introduced the concept of the food web (which he called the food cycle). He noted, among other things, that in food chains and food web there was a pattern of increasing body size moving up the trophic levels; for example, from phytoplankton to small fish to larger fish. Because organisms with small bodies need less energy than larger-bodied organisms, a specific amount of energy is able to support the larger amount of smaller-bodied organisms at the bottom—explaining the pyramid shape which was later named the Eltonian pyramid.

1. An energy pyramid is a graphic model representing energy flow in an ecosystem. Each trophic level is comprised of different groups of organisms that are part of a food web. The base of the pyramid is wider than the top. 2. Many primary producers are needed to support the life forms in the levels above them in the energy pyramid. The further up the energy pyramid, the less consumers there are. 3. (a) False (b) False (c) True (d) True (e) True 4. Energy is used by living things to find food, move, sleep, reproduce, digest food or grow. 5. Teacher check 6. Human activity 7. biodiversity

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• This set of pages should be completed after pages 26–33.

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• Many modern ecologists no longer believe in the 'balance of nature'. They prefer to say that the natural state of any ecosystem should be undisturbed. Many believe it is preferable to refer to the preferred state of nature as an ecological balance.

• The energy pyramid is also called the biomass pyramid. (Biomass refers to the number of organisms within a particular habitat.)

Page 37

Teacher check

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• There are numerous websites which provide background information about the energy pyramid, including: <http://www. learner.org/courses/essential/life/session7/closer5.html>, <http:// www.vtaide.com/png/foodchains.htm> and <http://www.tutorvista. com/biology/energy-pyramid-for-kids>.

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Content focus:

Preparation

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• Allow the students to visit <http://www.vtaide.com/png/foodchains. htm> to read and hear background information about energy pyramids and to read about energy transfer in specific habitats. (Click on ‘energy pyramid’ in the notes.) Or watch a video at: <http://videos.howstuffworks.com/discovery/27995-assignmentdiscovery-energy-flow-video.htm>.

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• Students should be familiar with the term ‘ecosystem’ (a community of organisms interacting with one another and with the environment in which they live, as in a pond, a forest etc.).

• Some materials will need to be collected if students wish to use boxes (such as shoeboxes) layered on top of each other for their energy pyramid representations on page 37. Other materials such as paintbrushes, colour magazines etc. will also need to be collected.

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A food web is a series of organisms related by predator–prey activities and is a series of interrelated food chains. They show the movement of food energy along a number of interconnected pathways in an ecosystem. The energy pyramid The complex nature of food webs can be represented by an energy pyramid. An energy pyramid is a graphic model of the energy flow in an ecosystem. Each trophic level represents different groups of organisms that compose part of a food web. The base of the pyramid is wider than the top as a reminder of two things:

An example of an energy pyramid in a water habitat

r o e t s Bo r e p ok u S tertiary consumers: heron (carnivores)

1 unit of energy

secondary consumers: small carp (carnivores)

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• A greater amount of primary producers are needed to support the increasingly smaller amount of life forms above them in the energy pyramid. The further up the energy pyramid, the less consumers there are.

10 units of energy

primary consumer: tadpoles (herbivores)

100 units of energy

• More energy exists at the lower trophic levels than at the top levels. primary producers: green algae Each group in a food web removes 1000 units of energy useful energy, so less is available to the levels above. Scientists have estimated that an average of only 10% of the energy that exists in a level is passed to the next level of the energy pyramid. The consumers at the top of a food energy pyramid, as a group, have much less energy available to them than those closer to the bottom. As such, the number of toplevel consumers are relatively few in most communities. Eventually, the amount of useful energy left isn’t enough to support another level of consumers. For this reason, most energy pyramids (and food chains) have a maximum of four or five levels.

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The balance of nature

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A number of different species share the same ecosystem, depending on each other for food as energy. This interdependence helps to maintain the balance of life. For example, if there are too many grasshoppers competing for plant food, some grasshoppers are unable to find sufficient food to survive and eventually die. With fewer grasshoppers eating them, the plants multiply and become more plentiful. However, fewer grasshoppers also means less food for field mice to eat and some mice die. When there are fewer mice, the amount of grasshoppers increases again. This process helps to maintain the balance of nature. The actions of humans, however, can often disrupt the balance of nature.

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As we can see, when the size of one group of organisms in a food web changes, other groups are affected. If one food source disappears, it can be difficult for the other organisms to find enough food. A healthy ecosystem is one in which no one level of consumer or producer places overwhelming stress on another. The variety of species of plants, animals and microorganisms in an ecosystem is called biodiversity, and is another sign of a healthy environment. The greater the biodiversity in a specific environment, the less likely it is that any part of the food web will become extinct. Food webs are intricate structures which show a multitude of species can share the same habitat and survive together for many years. R.I.C. Publications®

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What else do food webs show? – 1

What else do food webs show? – 2

tertiary consumers (carnivores) 1 unit of energy

Use the text on page 35 to complete the answers.

secondary consumers (carnivores)

1. Write an explanation to describe what an energy pyramid is, what it looks like and what it shows.

100 units of energy primary producers (plants) 1000 units of energy

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2. What is the significance of the wide base and narrow point of an energy pyramid?

3. State which are True or False. (a)

Few primary producers support many consumers.

(b)

Levels further up the energy pyramid have more consumers.

(c)

More energy is available in the lower levels of the energy pyramid than the higher levels.

(d) (e)

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4. Suggest possible reasons why only a percentage of energy is passed to consumers on the next trophic level of an energy pyramid. What has the energy been used for?

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Biological sciences

10 units of energy primary consumers (herbivores)

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5. Explain how the balance of nature can be achieved.

6. What main factor can influence the balance of nature?

7. Which term describes the variety of species of plants, animals and microorganisms in an ecosystem? AUSTRALIAN CURRICULUM SCIENCE

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1. Read the information and view images of different ways to represent energy pyramids at each of the websites provided. Copy each representation into the relevant box. (b) <http://www.education.com/science-fair/ article/food-chains/>

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(a) <http://www.eduweb.com/portfolio/ earthsystems/food/foodweb2.html>

2. Evaluate each website's representation for: the amount of information presented.

(a) (b)

(a)

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3. Complete the information to plan your own energy pyramid of a specific ecosystem. Use one of the formats above or a 2-D style similar to that on page 35. You will need to research information about the different organisms to include in each trophic level of the pyramid. (a)

Format selected:

(c)

Primary producers:

(d)

Primary consumers:

(e)

Secondary consumers:

(f)

Tertiary and/or quaternary consumers (if relevant):

(g)

Material required:

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(b) Ecosystem chosen:

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4. Once completed, present your energy pyramid to the class or a small group. 5. In comparison to other energy pyramid representations, evaluate your own. Poor

Average

Good

Very good

Excellent

6. On the back of the worksheet, list any improvements or changes you would implement for the next time. You can also suggest a different style of representation you would use. R.I.C. Publications®

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Biological sciences

Plan a different energy pyramid of your own

What part do microorganisms play in a food web?

Inquiry skills focus:

• The smaller pieces of each plastic bottle will be discarded. A support for the styrofoam circle can be constructed by cutting the base from another (smaller) plastic bottle. This is placed rim-side down in the base of the microcomposter. The disc must fit tightly so no compost or materials slip into the aeration space below. Other ‘bulking agents’ apart from wood shavings include newspaper strips or straw. The stocking will contain any insects that breed inside the bottle. The bottle can also be wrapped in an old towel to keep it warm.

Microorganisms are tiny organisms that can not be seen by the naked eye. Microorganisms play an important part in a food web by recycling energy from dead plants and animals. Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• Evaluate the experiment after completion. Discuss whether it was a fair test, what worked and what didn’t, and what could be improved if the experiment was repeated again. Teachers may need to revise for students what a fair test is.

r o e t s Bo r e p ok u S Answers Page 40

• Although both detrivores and decomposers perform similar functions, this set of pages deals exclusively with decomposers. The main difference between detrivores and decomposers is that detrivores eat the organic matter, while decomposers secrete enzymes to digest the organic matter and absorb the molecules (as bacteria and fungi do). (Refer to page 27 for information about detrivores and decomposers.)

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• Students can devise their own experiments about the use of microorganisms in different methods of composting. For example, the students could compare the progress and quality of compost or appearance of microbes made in a homemade mixture to a commercial mix.

• Microorganisms require a microscope to be viewed. Until Anton van Leeuwenhoek's improvement of the microscope in 1675, it was not known that they existed. They are also the oldest form of life on Earth. Microorganisms are found everywhere—in water, soil, hot springs, on the ocean floor, in the air and atmosphere, inside humans and animals, and in rocks in the Earth’s crust.

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1. Answers will vary but will be similar to ‘tiny organisms invisible to the naked eye’. 2. (a) enzyme (b) ecosystem (c) complex (d) desertification 3. Teacher check 4. (a) Enzymes are chemicals produced by decomposers (microorganisms) to break down and digest dead material and animals. (b) Carbon dioxide is released into the air when microorganisms break down organic matter. This is then used by plants for photosynthesis (to produce food). 5. Possible answers: short term – loss of nutrients available to plants, fire hazard, suffocate new plants; long term – desertification, imbalance of nature, food supplies affected.

• Photosynthesis is the chemical process that green plants use to produce sugars and oxygen from carbon dioxide and water (by way of solar energy) for use in processes such as tissue building. Preparation

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• Visit <http://www.teachersdomain.org/resource/tdc02.sci.life. oate.decompose/> to watch a short video about the role of decomposers.

Page 41

• This set of pages would be best completed after pages 26–37 so that the students have some background knowledge of food chains and webs.

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The microorganisms in the bottle should break down the materials into usable compost. The compost created in the bottles, because of their size, may not look like compost from larger compost bins or store-bought bags. The volume of the material in the microcomposter should shrink by about 1/2 to 2/3. The original material should not be recognisable. The material can remain in the bottle for months or used to start a new pile of compost.

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• The students will need to collect the materials required for the experiment on page 41. A number of different, readily-available thermometers should be trialled to see which are suitable. Sugar and candy thermometers, baby bath thermometers or scientific thermometers (if available) could be used. The lessons

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Content focus:

• Page 41 involves microcomposting. Refer to <http://www. composterconnection.com/site/micro-composting.html>, which provides a number of different versions of microcomposters and more background information for the experiment.

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An organism is any form of animal or plant life. ‘Micro-’ is a Greek-derived prefix meaning ‘an object as being smaller than scale of focus’. Microorganisms can then be defined as tiny organisms which can not be seen by the naked eye. Because they are so small, they make up the largest number of living organisms on Earth. Microorganisms are quite diverse. Some eat other organisms and others make their own food by using the energy of the sun or by chemical reaction. They can be solitary or live in colonies, and they can reproduce sexually (two microbes mix and create a new microbe) or asexually (one microbe splits into two identical pieces). Most are single-celled, but others are multicellular. Most microorganisms reproduce very quickly. The most common forms of microbes include bacteria, fungi, protozoa, algae, microscopic animals and nematodes.

r o e t s Bo r e p ok u S

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Teac he r

In a food web, primary producers (plants) are eaten by primary consumers, who are in turn eaten by secondary consumers. Secondary consumers are eaten by tertiary consumers, who are sometimes eaten by quaternary consumers. The chain of energy transfer continues until, eventually, top-level consumers die. The plants and animals contain chemicals (another type of energy) that are the basic building blocks of life. When plants and animals are dead, microorganisms such as bacteria and fungi, which we call decomposers, perform an essential function in the transfer of energy by recycling these chemicals for use by other organisms in the food web. Like other consumers, microorganisms that are decomposers can not produce their own food. As decomposers feed on the remains of dead animals and plants and animal waste products, they break down the complex organic compounds those organisms are made of into simple nutrients for food. They do this by producing chemicals called enzymes that digest the dead material. After absorbing the substances they require for growth, the remaining broken-down materials are returned as nutrients to the soil (as a type of waste product). These nutrients can be used again by plants, continuing the energy transfer chain. During the process of decomposition, microorganisms, for example, release carbon dioxide which can be used by plants for photosynthesis (to create food for the plants).

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Without decomposers to break down waste products and dead animals, organic matter would build up, preventing plants from receiving the nutrients they need to survive. A blanket of leaves or dead plant material and animals would suffocate new plants, or become a potential fire hazard. When finally blown away, the layer of materials would leave the soil bare and possibly lead to desertification. The removal of microorganisms from a food web or chain would result in a lack of nutrients for plants, Food web causing many to die. With insufficient plants Microorganisms (primary producers) to eat, herbivore consumers would die. This would then lead to a lack of food for carnivores and omnivores. This collapse of the food web would seriously Carnivores affect food supplies for all animals, including humans.

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Herbivores

Microorganisms, or decomposers, are nature’s clean-up crew, but despite this they are often not shown in a food chain or food web.

Plants

Microorganisms R.I.C. Publications®

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What part do microorganisms play in a food web? – 1

What part do microorganisms play in a food web? – 2 Use the text on page 39 to complete the following.

2. Find words in the text that mean: (a)

any protein that increases or decreases the rate of a chemical reaction.

(b)

a community of organisms interacting with one another and with the environment

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in which they live. (c)

complicated; intricate.

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the degradation of land in arid, semi-arid, and dry sub-humid areas so that plants are

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(d)

unable to grow.

3. Explain how a food web works, including the role microorganisms (decomposers) play.

4. Explain: the function of enzymes in microorganisms.

(b)

the function of carbon dioxide in the decomposition process

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(a)

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Biological sciences

1. Use your own words to write a definition of a ‘microorganism’.

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5. Without microorganisms to break down waste products and dead animals, problems would occur. Write two: •

short-term effects.

•

long-term effects.

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Microcomposting You will need: â&#x20AC;˘ 2-litre and 3-litre plastic drink bottles â&#x20AC;˘ craft knife â&#x20AC;˘ nail â&#x20AC;˘ small container (about 5 cm tall) to fit inside bottle sticky tape â&#x20AC;˘ wood shavings or 1 to 2 cm-sized pieces of cardboard egg cartons, cardboard or wood, soaked in water and drained of excess water â&#x20AC;˘ thermometer to fit into top of bottle, long enough to reach centre of compost â&#x20AC;˘ chopped vegetable scraps, garden weeds or air holes grass clippings â&#x20AC;˘ polystyrene plate or tray â&#x20AC;˘ wide, clear tape â&#x20AC;˘ scissors â&#x20AC;˘ nylon stocking â&#x20AC;˘ rubber band â&#x20AC;˘ marker

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Small container; e.g. spray can lid/or base cut from small plastic bottle.

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Procedure

Equal quantities of vegie scraps, wood, wood shavings and/or grass clippings (not tightly packed).

í˘ą Use knife to cut top from the 3-litre bottle just below shoulder of bottle. Cut 2-litre bottle just above shoulder of bottle. Using larger pieces of bottles, the top from one should fit tightly over the bottom of other. Check, then take apart until inside is assembled.

í˘˛ Place small container upside down in bottom of bottle to create a stand to support circular tray that will hold compost.

í˘ł Trace and cut out a circle which is the diameter of bottle from polystyrene plate. It should fit

ÂŠ R. I . C.Publ i cat i ons indicate position of circle. â&#x20AC;˘ f oand rr ev i efrom wbottle, pu r p os e so l y â&#x20AC;˘ below the Remove stand foam circle then make air holes onn side of bottle snugly inside bottle. Use nail to punch holes through circle for aeration.

í˘´ Place stand in bottle, then place foam circle on top of stand. Mark bottle on outside to í˘ľ

mark. (Heating nail carefully will melt holes through plastic.) Do not make holes in bottom of bottle! Reassemble microcomposter.

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í˘ś Mix equal quantities of shavings or cardboard pieces, vegetable scraps, weeds or grass

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clippings to provide food for the microbes and fill microcomposter. Do not pack down! Equal quantities will keep mix light. Shavings or cardboard pieces will allow air flow.

í˘ˇ Replace top piece of bottle and seal with tape.

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í˘¸ Cover mouth of bottle with a piece of nylon stocking and secure with rubber band. Keep shavings and scraps moist. Predictions

1. What will happen to the material in the microcomposter? What will it be like?

2. Predict how long the process will take. Results and conclusions 1. Track the daily progress of your compost, using temperature readings taken when the thermometer is inserted into the mixture. Take note of the type of materials used, the moisture levels, the amount of air flow and the type of insulation used. 2. Write a conclusion stating the quality of the compost created and how it occurred. R.I.C. PublicationsÂŽ

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rubber band

What impact do humans have on the environment?

Content focus: Inquiry skills focus:

Answers Use and influence of science; Nature and development of science The impact humans have on their environment Questioning and predicting Planning and conducting Processing and analysing data and information Communicating

Background information

Page 44 1. ... purposely try to modify the greater environment to suit their needs/upset the balance maintained in an environment. 2. pollution, climate change, damage to land, depletion of the ozone layer 3. Refer to table below.

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• Because of the interdependence of the populations within a food chain, a change to a link in a food chain will affect the others.

• Industrialisation is the introduction and development of large-scale industry in an area OR the organised action of making of goods and services for sale. • Many scientists believe climate change is responsible for the loss of habitat for polar animals as ice caps melt. Some concerns have also been expressed that the Gangotri glacier that feeds the Ganges River (which sustains millions of people in India) is melting and may eventually cause the river to dry up.

CAUSE

RESULT

• industrialisation

• increased demand for the world’s resources for production of goods and services

• improvements in medicine and food production

• increase in population growth

• burning non-renewable fossil fuels

• damaging gases released into the air

• industrial and domestic waste released into rivers and oceans

• change to marine life ecosystems

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• emissions from fossil fuel combustion, the use of aerosols, ozone depletion, deforestation

• increase in carbon dioxide levels

• increase in temperature

• disruption to weather patterns

• Desertification is the process by which fertile land turns into barren land or desert.

• Cyanobacteria are found in all environments including fresh water, oceans, rocks and soil. They are responsible for producing about 20–30% of Earth’s photosynthetic productivity and convert solar energy into biomass-stored chemical energy. Ozone layer depletion can destroy this bacteria.

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• Visit <http://www.wigry.win.pl/bobry/wplyw_en.htm> to read about the impact beavers have on their own environment and <http:// www.nceas.ucsb.edu/globalmarine> to view a map of the impact of humans on the oceans of the world. Preparation

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• land clearing

• reduced amount of vegetation producing oxygen

• rice cultivation, coal mining, oil drilling, cattle and sheep ranching

• methane gas added to greenhouse gases

• fertilisers and pesticides

• make their way into rivers and lakes, affecting aquatic life

• chlorofluorocarbons produced by industrial and domestic use

• depletion of the ozone layer

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Teacher check. The pseudo-carbon footprint calculator aims to make the students aware of their own actions. Most carbon footprint calculators include information from energy-usage bills and some also include information about car and aeroplane travel to make a calculation. Column 1 contains actions which are carbon-friendly and Column 2 lists less desirable actions. Students should evaluate their impact on the environment and plan a similar calculator of their own.

• After the students have read the text on page 43, discuss and explain the concepts. Some additional information might be needed for some concepts. • Before completing the pseudo-carbon footprint calculator, students should predict how environmentally friendly they believe their actions are on a scale from 1 to 10 and compare this to their final calculation on the pseudo-carbon footprint calculator.

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• reduction of population of many marine species

4. Through scientific studies and research 5. Human survival depends on maintaining a healthy environment because humans are an integral part of food webs.

• Some background knowledge about theories of climate change and global warming may be useful to assist student understanding of concepts. The lessons

• oceans absorb carbon dioxide emissions

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Biological sciences

Science as a Human Endeavour unit:

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Humans are an integral part of food chains and webs, and unlike the other components, are the only organisms that purposely try to modify the greater environment to suit their needs. Unfortunately, human actions can easily upset the balance maintained in an environment.

Pollution

Climate change

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Teac he r

Since the 18th and 19th centuries, industrialisation has resulted in an increased demand for the world’s resources for the production of goods and services. There has also been an increase in population growth due to improvements in medicine and food production. Along with industrialisation and increased population, there has been an increased need to burn fossil fuels for energy for manufacturing, transportation, heating, cooling and other applications, both in factories and at home. Burning non-renewable fossil fuels releases damaging gases into the atmosphere, creating air pollution and affecting humans, bird and animal life, and vegetation. Waste from industrial and domestic use releases pollution into rivers and oceans, and damages the quality of land, changing ecosystems for aquatic and soil life. Climate change is the change in global temperatures and precipitation over time due to natural factors or human activity. Most scientists agree that some of the human activities affecting climate change include an increase in carbon dioxide levels due to emissions from fossil fuel combustion, the use of aerosols, ozone depletion and deforestation. Greenhouse gases trap heat in the atmosphere and cause an increase in temperatures, disrupting weather patterns and resulting in floods and drought. Increased carbon dioxide in the air can cause changes to the growth of plants. Meanwhile, increased absorption of carbon dioxide into oceans (about 50% of total absorption) is affecting the growth of coral reefs, the production of jellyfish, the ability of some marine life to maintain protective shells, and reducing the population size of many marine species.

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Damage to land

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As human population size increases, so does the need for land for urban development, and logging, mining and agriculture. Land clearing can cause deforestation, soil erosion, desertification and reduce the amount of vegetation releasing oxygen back into the air. Land clearing destroys the habitats of species of flora and fauna, leading to their possible endangerment or extinction. Methane gas from rice cultivation, coal mining and oil drilling, and cattle and sheep ranching also adds to greenhouse gas levels. Fertilisers and pesticides used to benefit food production can make their way into rivers and lakes and affect aquatic life.

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Depletion of the ozone layer

Chlorofluorocarbons (CFCs) and other gases produced through industry and domestic use, can deplete the ozone layer. These are released from refrigeration systems, air conditioning, foam, and solvents. As CFCs rise into the atmosphere, they break down the ozone molecules that form the ozone layer. This allows more harmful UV rays to enter the atmosphere, causing damage to humans (such as skin cancer, cataracts and weakened immune systems), reduced crop yields and disruptions to marine food chains. Scientific studies and research have helped humans become aware of their impact on the environment. Human survival depends on maintaining a healthy environment, and as a result steps have been taken to minimise human impact. What steps could you, personally, take to minimise your impact on the environment of your part of our world? R.I.C. Publications®

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Biological sciences

What impact do humans have on the environment? – 1

What impact do humans have on the environment? – 2 Use the text on page 43 to complete the following. Humans are the only components of a food chain or food web to ...

2. List four major types of human-caused environmental damage. •

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•

3. Complete the table to show the cause and result of each human action. CAUSE

RESULT

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Teac he r

• increased demand for the world’s resources for production of goods and services

• improvements in medicine and food production

• damaging gases released into the air

© R. I . C.Pu bl i cat i ons • change to marine life ecosystems f o rfuel r e vi ew pur posesonl y• • emissions• from fossil combustion, the use of aerosols, ozone depletion, deforestation • disruption to weather patterns

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Biological sciences

1. Complete the sentence.

• reduction of population of many marine species

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• reduced amount of vegetation producing oxygen

• rice cultivation, coal mining, oil drilling, cattle and sheep ranching

• make their way into rivers and lakes, affecting aquatic life • depletion of the ozone layer

4. How has science helped make us aware of our impact on the environment?

5. Why is it important for humans to maintain a healthy environment? AUSTRALIAN CURRICULUM SCIENCE

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Calculate your carbon footprint Biological sciences

A carbon footprint measurement shows the approximate total of greenhouse gas (carbon dioxide) emissions caused by a person or group. Greenhouse gases are partly the result of human activities such as using transport, farming; and the consumption of food, fuels and materials. 1. Use the pseudo-carbon footprint calculator to gauge your impact on the environment. Tick the appropriate boxes in each column as they apply to you and your family.

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• Main source of power is mains-supplied gas or electricity

• Shower daily

• Bathe daily

• Energy-efficient shower head

• Television in own room for use

• Lights switched off when leaving room • Electrical equipment switched off at wall when not in use

• Computer in own room for use • CD player or system in own room for use

• Travel mainly by car

• Walk, cycle or carpool to get to places

• Consume free-range products • Consume quantities of organically-grown fresh fruit and vegetables

• Regularly consume take-away food

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• Solar power used to heat hot water or swimming pool

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ENERGY

COLUMN 2

© R. I . C.Publ i c t i oconsume ns carbonated drinks •a Regularly FOOD • Regularly consume fresh water • Consume large quantities of meat AND •f o r r e v i e w p u r p o sesonl y• • Purchase food with minimum DRINK • Regularly consume bottled water

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• Reuse paper and plastic bags for other purposes • Buy and use recycled paper and plastic products WASTE • Recycle plastic, aluminium and glass products • Add vegetable peelings and scraps to compost heap

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• Occasionally eat at restaurants which serve dishes made from imported ingredients

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packaging • Minimum wastage when consuming food

• Regularly consume processed foods

• Regularly buy up-to-date fashions • Obtain a new plastic shopping bag with each new purchase • Buy new paper to wrap presents and parcels • Purchase store-bought cards to give for special occasions • Use recycled items to create artworks, projects or useful items

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• Donate clothing to charity bins

2. Give yourself 10 points for each tick in column 2 and subtract 5 points for each tick in column 1. Your aim is to achieve the smallest number possible. 3. Visit one of the websites listed to calculate a more accurate assessment of your carbon footprint and that of your family: • <http://www.carbonneutral.com.au/carbon-calculator.html?gclid=CO60_7qpm6gCFQrgbg odeRjeHg> • <http://www.carbonfootprint.com/calculator.aspx> • <http://www.1degree.com. au/carbon_calculator>. R.I.C. Publications®

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What are some examples of human impact on the environment?

Inquiry skills focus:

Answers Use and influence of science Examples of human impact on the environment including the introduction of the cane toad and rabbit to Australia, and commercial palm oil harvesting Questioning and predicting Planning and conducting Processing and analysing data and information Communicating

Background information

Page 48 1. (a) gelatinous (b) voracious (c) toxic (d) gene (e) biological control (f) biodiversity (g) ultraviolet 2. Answers should be similar to: cane toads have a high reproduction rate, producing up to 25 000 eggs in each clutch; cane toads are voracious feeders, eating insects, frogs, small reptiles, mammals and birds; cane toads have toxic glands which cause death to many native fauna. 3. Scientists are trying to create a gene to reverse the sex of female cane toads, making an all male population which would eventually die out. Ultraviolet light is being used to attract moths that cane toads eat to bring the toads together to enable them to be easily captured. 4. Feral rabbits eat the native flora that bilbies and bandicoots eat. As such, there is less food for bilbies and bandicoots. 5. Farmers attempted to destroy rabbit warrens, and poison and shoot rabbits. 6. In 1907, the 1833-kilometre rabbit-proof fence was built. In 1950, a virus called myxomatosis killed most rabbits. In 1996, another virus, called rabbit calicivirus, was introduced. 7. Scientists are trying to develop a virus which causes sterility in rabbits.

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• Despite their widespread numbers, cane toads do have some predators who have learned to capture and feed on them in unusual ways. Some birds are able to flip cane toads onto their backs to attack the belly and avoid the parotid glands. The native meat ant is believed to be immune to the cane toad’s poison so prey on young cane toads. The native freshwater turtle (Myuchelys latisternum or saw-shelled turtle) is the most successful cane toad predator. They swallow most cane toads whole, while larger toads are shredded first with their front claws.

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Page 49

• Currently, the most humane method of disposing of cane toads is by trapping or freezing. A cane toad is unable to survive temperatures below 5 °C. When placed in a container in a freezer, the metabolism of the cane toad slows down, and it becomes sleepy and then unconscious. Eventually, ice crystals form in the cells of its body, perforating the walls and killing the toad.

• Demand for palm oil products increasing; it produces 10 times more oil per unit area than soybeans, rapeseed etc. • Cooking oil (locally), exported for commercial use—soap, washing powder, cosmetics, snack foods; converted to biodiesel fuel • Main source of income in areas where few industries exist for employment

• The CSIRO is the Commonwealth Scientific and Industrial Research Organisation: a national government body for scientific research in Australia.

• Causes deforestation in tropical forest areas responsible for one-third of CO2 emissions. This causes a significant increase in greenhouse gas emissions.

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• Visit <http://www.environment.gov.au/biodiversity/invasive/ publications/cane-toad/2008.html> to read a report by the CSIRO about research into biological ways to control the cane toad. Read about one scientist’s suggestion at <http://www.usyd.edu.au/news/ science/397.html?newsstoryid=2292>. Preparation

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Biological sciences

Science as a Human Endeavour unit: Content focus:

• Habitat destruction affects endangered species such as Sumatrian tiger, Asian rhinoceros and Sumatrian orangutan. • Reduces biodiversity

• Reduce peat bogs under forests which store carbon

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• Destroys cash crops such as fruit and rubber trees • May promote heart disease because palm oil is high in saturated fats and low in polyunsaturated fats; change cholesterol levels • Human rights issues such as low pay and poor working conditions

• The video of the rabbit plague on a farm during the 1960s at <http://aso.gov.au/titles/documentaries/life-sheep-farm/clip2/> could be a useful way to introduce the topic.

• Ethical and moral considerations in removing land from indigenous people • Biodiesel projects funded by carbon credit projects • Steps to make harvesting a sustainable production

The lessons

• Companies stop purchasing palm oil from high-risk planations Some possible internet sources include:

• The website <http://library.thinkquest.org/03oct/00128/en/rabbits/ history.htm> provides interactive activities, including access to maps of Australia which show the coverage of feral animals, which teachers and students may find useful throughout the lessons.

• <http://en.wikipedia.org/wiki/Environmental_impact_of_palm_oil> • <http://en.wikipedia.org/wiki/Palm_oil> • <http://www.mongabay.com/borneo/borneo_oil_palm.html> • <http://www.scientificamerican.com/article.cfm?id=harvesting-palm-oiland-rainforests> • <http://www.fastcompany.com/1734847/biofuel-harvesting-palm-oilplantations-are-driving-co2-levels-up-study>.

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Because of the interdependence of populations in a food chain, human changes can have a significant, and often negative, effect on other populations in an environment. Read about some examples. Rabbits were brought to Australia with the arrival of the First Fleet in 1788 as a source of meat for the settlers. In 1859, wild rabbits were released on a property in Victoria as sport for hunters. The released rabbits reproduced rapidly, causing a rabbit plague throughout the state. Feral domesticated rabbits and wild rabbits soon established massive populations, with no natural predators to contain them. Soon large areas of vegetation were destroyed, including feed for livestock and that which native fauna such as the bilby and bandicoot fed off. The removal of vegetation also caused soil erosion and the removal of nutrients from the soil. Eradicating rabbit warrens, and poisoning and shooting the pests failed to significantly reduce numbers.

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In 1935, the cane toad (Bufo marinus) was introduced into Australia from Hawaii as a biological control for the native cane beetle which was ravaging the valuable sugar cane industry in the state of Queensland. From about 100 original cane toads, the population has now reached a staggering 200 million, due in part to the fact that cane toads can produce up to 25 000 eggs in one long gelatinous clutch. Their population is believed to be able to spread at a rate of around 30–50 kilometres per year and is capable of tolerating a broad range of environmental conditions.

In 1907, a massive rabbit-proof fence was built, covering 1833 kilometres. Unfortunately, between the start and finish of its construction, rabbits had entered the area the fence was trying to keep them from.

Cane toads are voracious feeders and have a varied diet, and so do not depend exclusively on one species for survival. Their prey includes insects, frogs, small reptiles, mammals and birds. They will also eat human and animal faecal matter, so their bodies can harbour salmonella, harmful bacteria and parasites.

myxomatosis which successfully killed about 95% of the rabbits in some areas. However, after about 15 or 20 years, rabbits developed a resistance to the virus. Attempts to introduce the European rabbit flea in 1957 and 1966, and the Spanish rabbit flea in 1993 to help spread the virus were also unsuccessful.

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At all stages of their life cycle, cane toads are highly toxic to predators, causing death to many within minutes. Parotid glands on the sides of the head produce creamy-white venom, which the animal releases when provoked.

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In 1996, another virus—Rabbit Haemorrhagic Disease or rabbit calicivirus—was introduced which reduced populations, but again, rabbits built up resistance.

Cane toads are having an extremely detrimental effect on the environment and its biodiversity across the continent. The endangerment of the northern quoll and some reptile species is believed to have been caused by the cane toad.

Currently, research is being carried out to develop a virus which causes sterility in rabbits. Rabbits remain one of Australia’s worst introduced pests, causing millions of dollars worth of damage to the agricultural and livestock industries each year, and having an enormous impact on the native flora and fauna of Australia.

Scientists are currently studying the feasibility of biological controls for this diabolical pest. Some research has been conducted into the creation of a gene to reverse the sex of the female toad, making an all male population which would eventually eliminate the species in Australia. Ultraviolet light has been used to attract the moths that cane toads eat, luring the toads and making it easier to capture them. R.I.C. Publications®

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Biological sciences

What are some examples of human impact on the environment? – 1

Use the text on page 47 to complete the answers. 1. Find the words in the information text which mean: (a)

jelly-like.

(b) greedy, ravenous.

(c)

poisonous.

(d) the unit of biological inheritance.

(e)

the use of natural enemies to reduce the damage caused by a pest population.

(f)

the variety of species of plants, animals and microorganisms, and the ecosystems

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they make up, often considered in relation to a particular area. (g)

beyond the violet, as the invisible rays of the spectrum with wavelengths shorter than the violet end of the visible spectrum. Cane toad's parotid gland

2. Name three features of cane toads that have contributed to their rapid spread and detrimental impact on fauna in Australia. •

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• •

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What are some examples of human impact on the environment? – 2

4. Explain how feral rabbits have had an effect on the population size of the native bilby and bandicoot.

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5. What measures were initially used by farmers to try to reduce the rabbit population? 6. Name one structural and two biological controls which are/were attempted to try to eradicate feral rabbits, and when these were trialled. • • • 7. What scientific research is being undertaken to try to solve the rabbit pest problem?

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Use the questions in the table to complete a research activity about the human impact of palm oil harvesting in South-East Asia. Why is palm oil important? What products are made from it?

Why is the income from palm oil harvesting important to its farmers?

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What are the main environmental aspects of palm oil harvesting on the local environments where it is farmed and the earth in general?

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What are the health benefits, if any, of using palm oil?

What are some of the possible social problems of palm oil harvesting?

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What, if anything, is being done to counteract the environmental impact of palm oil harvesting?

What sources were used for your research? List the most important sources below.

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Biological sciences

The human impact of palm oil harvesting

How can traditional and Western scientific knowledge help with managing the environment?

Content focus:

Inquiry skills focus:

• Students should always be aware of what a fair test is when conducting experiments such as that on page 53, and should become accustomed to evaluating the success or failure of each and consider any improvements and changes if the experiment was repeated.

Use and influence of science; Nature and development of science Scientific knowledge and traditional land management practices of Aboriginal and Torres Strait Islander people can be used to manage the environment in a sustainable manner. Questioning and predicting Planning and conducting Processing and analysing data and information Communicating

Answers Page 52 1.

TRADITIONAL ABORIGINAL AUSTRALIAN LAND MANAGEMENT PRACTICES

r o e t s Bo r e p ok u S Advantages

• sustainable

• Not dependent on one particular food type • Moved to new areas as needed

Background information

• Left behind seeds and eggs to ensure survival of species

• Mostly used environmentally-friendly methods to capture prey

• It is believed that in some instances, Aboriginal Australians deliberately cut holes in trees for possums so that they could later be raided for food.

• Left land fallow after harvesting • Promoted growth of plants to attract grazing animals to hunt

• The demise of the ‘megafauna’ is thought to have been brought about by constant hunting by Aboriginal Australian peoples. Refer to websites such as <http://www.convictcreations.com/aborigines/ megafauna.html>.

Disadvantages

• Poisonous plants used to kill fish in waterholes • Firestick agriculture caused loss of native plants, replaced them with desired plants and may have contributed to ‘drying’ of continent.

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MODERN AGRICULTURAL PRACTICES Advantages • Large-scale, monocultural farming means only looking after one product.

Disadvantages

• Heavy dependence on machinery

• Read about some archaeological discoveries—which suggest Aboriginal Australians may have practised some forms of agriculture, such as diverting water to feed quandong trees, and storing food—at <http://www.janesoceania.com/australia_ aboriginal_agriculture/index1.htm>.

• Better quality products • Organic farming

• Integrated pest management • Selective breeding

• Visit <http://www.publish.csiro.au/onborrowedtime/sections/index. html> to complete two interactive projects to maintain a sustainable ecofarm and ecoforest.

• Genetically-modified foods

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• The types of traditional foods eaten by Aboriginal Australians, how they were prepared and how they were obtained, varied from group to group and region to region. Certain ‘taboo’ foods might also have contributed to the sustainability of food sources. Preparation

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• High use of fossil fuels

• Higher crop yields

• Overuse of pesticides and fertilisers causes soil degradation and water pollution. • Increase in water scarcity as demand for irrigation increases • Livestock increase greenhouse gases, cause deforestation and reduce biodiversity.

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Science as a Human Endeavour unit:

2. (a) genetically-modified food (b) organic farming (c) selective breeding (d) integrated pest management Page 53

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• The students will be testing the effect of different pollutants on soil quality and plant growth. Standard fertiliser prepared correctly should show improvement in plant growth with few detrimental effects. Longterm soil benefits may not be obvious over a short time. Students could consider increasing the dosages and frequency of application in a different experiment of their own. The students should see changes to Pots 1 to 3 and little to Pot 4. Soil texture should change in Pots 1 and 2. The plants may die in Pots 1 to 3.

• The students may have some background knowledge of traditional Aboriginal Australian methods of obtaining food. Gauge their knowledge by discussion.

• Prepare the pots of wheat grass for use in the experiment on page 53 a few weeks ahead of time to ensure adequate growth of the plants. Other suitable plants can also be used if available. The lessons • The website <http://www.funsci.com/fun3_en/exper1/exper1. htm> includes some excellent, but simple, experiments about soil erosion, soil composition, biospheres and ecospheres, soil ecosystems and the production of oxygen by photosynthesis. These may act as a good introduction to environmental issues—both human-caused and natural.

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For thousands of years, the Aboriginal Australian peoples used the land to supply all their needs: food, clothing and shelter. They lead a sustainable lifestyle based on their knowledge of the diversity of plants and animals in the environment in which they lived. Also, their beliefs developed a deep spiritual attachment to the land.

could regenerate. Large areas of bushland were burnt to promote the growth of certain types of plants to attract grazing animals such as kangaroos. However, this greatly changed the appearance of the Australian bush. Many native plants were replaced by fire-resistent plants such as grass trees, eucalypts, acacia or grasses. Firestick agriculture is believed to have contributed to the ‘drying’ of the continent.

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As traditional hunter-gatherers, they ate a wide variety of foods including wild fruit, nuts, berries, edible leaves and plant roots, and eggs. They were not dependent on one single type of food. They moved to new areas to utilise food resources as necessary. When leaving an area, they would leave behind plant seeds or eggs in birds’ nests to ensure the survival of each species in that area, and for continued provision of food when they returned.

Today, agriculture is predominantly largescale and monocultural, as farmers grow specific crops for a worldwide marketplace and its growing population. Modern agricultural techniques are used to maintain the land for grazing animals and growing crops, and to increase crop yields and produce better-quality products.

They are believed to have hunted snakes, fish, goannas, tortoises, possums, kangaroos, ducks, lobsters, shellfish, witchetty grubs, crabs and seals. In some regions, eels and fish were caught using permanent or traps. Also there is evidence that yams, bananas, taros and coconuts were intensively farmed.

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The heavy dependence on mechanisation in modern agriculture places high demands on fossil fuel use. The overuse of pesticides and fertilisers causes soil degradation and water pollution. Water scarcity is increasing as demand for irrigation increases, livestock farming is one of the largest contributors to greenhouse gases, and a cause of deforestation and reduction in biodiversity.

Predominantly, the methods of capturing prey were environmentally-friendly. Nets were used to capture fish and birds, sticky sap was placed on branches to prevent birds from escaping, or seeds were used to attract them. Snares were set and water birds captured by swimming underwater and seizing their legs. Fish were speared or caught using bark-string fishing line. Sometimes, poisonous plants were placed in water holes to kill fish for collection.

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In the future, it will be necessary for agricultural practices to change to more sustainable methods to reduce the negative impact on the environment. Organic farming, integrated pest management, selective breeding and genetically-modified foods (crops developed with specific genetic qualities) are all scientific approaches to more environmentally-friendly land management.

'Firestick agriculture' was a major method of obtaining food. Fire made areas safe from snakes or was used to drive out animals (such as possums and kangaroos) from their hiding places so they could be killed. Torres Strait Islanders are believed to have cleared the land by way of burning to then use it to cultivate bananas, taros, coconuts and yams. They then left it fallow after harvesting so the soil R.I.C. Publications®

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Traditional and Western scientific knowledge can both be used to care for the land while managing the land for sustainable farming.

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Biological sciences

How can traditional and Western scientific knowledge help with managing the environment? – 1

How can traditional and Western scientific knowledge help with managing `the environment? – 2 1. Compare the two agricultural methods by completing the table. Write using bullet points. Traditional Aboriginal Australian land management practices Advantages

Disadvantages

Modern agricultural practices Advantages

Disadvantages

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2. Match the correct scientific agricultural practice to each definition. • integrated pest management

• selective breeding

• genetically-modified food

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• organic farming

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Use the text on page 51 to complete the following.

(a)

Crop foods created for human consumption using plants modified in a laboratory that have enhanced characteristics such as increased nutritional content or resistance to herbicides

(b)

Farming with strict limits on the use of fertilisers and pesticides, hormones and antibiotics

(c)

The intentional breeding of plants and animals to produce offspring with particular, or improved, genetic traits

(d)

The control of pests using information about their life cycles and interaction with the environment through a series of evaluations, decisions and controls

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You will need: • 4 prepared pots of soil and wheat grass with saucers • 4 plastic jugs—one containing a mixture of one part vegetable oil to three parts water; the second containing a mixture of one part car washing liquid and three parts water; the third containing a double-strength mixture of liquid fertiliser (in the proportions listed on the container); and the fourth containing a standard mixture of liquid fertiliser (as listed on the container) Procedure

POT 1

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POT 3

POT 2

POT 4

Place the saucers underneath the pots to capture excess liquid.

Label each pot from 1 to 4. Pot 1 will have the vegetable oil and water mix poured into it.

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Pot 2 will have the car wash mix poured into it. Pot 3 will have the strong liquid fertiliser poured into it and Pot 4 will have the standard amount of liquid fertiliser poured into it.

You will be pouring liquid into each pot once a week over a period of one month and recording your observations of the plant and soil appearance and soil texture.

Predictions

What will happen to the wheat grass and soil in each pot? POT 1

POT 2 • wheat grass

• wheat grass

• soil

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Results and conclusions

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1. Pour each specified liquid into its appropriate pot as directed (once a week over a monthly period). Discard excess liquid in saucers sensibly if it builds up.

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2. Record your results in the table. POT 1 • wheat grass

POT 2

• wheat grass

• soil

• soil POT 3

POT 4

• wheat grass

• soil

3. On the back of the worksheet, record your conclusions and an explanation for the results obtained. R.I.C. Publications®

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Pollutant and fertiliser experiment

What are mixtures and pure substances? The lessons

The difference between pure substances and mixtures

Content focus:

• Explain that when a pure substance in its liquid form reaches its boiling point, any further input of heat energy converts the liquid to a gas. It does not raise the temperature of the liquid beyond its boiling point.

Planning and conducting Processing and analysing data and information Evaluating Communicating

Inquiry skills focus:

Background information

• When a mixture in liquid form is heated, the component with the lowest boiling point changes to a gas when its boiling point is reached. The temperature remains constant until all of that liquid has boiled away. Further input of heat energy then raises the temperature of the remaining liquid until the next boiling point is reached. This process continues until all of the mixture has boiled away.

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Answers

Page 56

1. (a) a homogeneous mixture (b) a compound (pure substance) (c) an element (pure substance) (d) a heterogeneous mixture 2. (a) gold, carbon (b) water, carbon dioxide (c) salt or sugar dissolved in water, stainless steel, air (d) instant coffee and sugar granules, oil and vinegar, milk 3. (a) A mixture is composed of two or more different substances that can be physically separated. Pure substances can not be physically separated. (b) If the liquid boils at one temperature, it is a pure substance. If it boils over a range of temperatures, it is a mixture. 4. The solid particles scattered through a suspension reflect the light and stop it from passing through. 5. properties 6. (a) a homogeneous mixture of two miscible liquids (b) mix 7. (a) fractional distillation (b) filtration (c) evaporation Science as a Human Endeavour question Use and influence of science • Russian scientist Mikhail Tsvet was trying to separate the hidden red and yellow pigments from the green leaves of deciduous trees.

• Each element has only one type of atom. Elements can exist as single atoms or as multiples of the same atom. Two or more atoms joined together are called a molecule. Compounds are molecules of two or more different types of atom.

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• Some useful websites are: − <http://www.elmhurst.edu/~chm/vchembook/106Amixture. html> − <http://www.chemistryforkids.net/help/pure-substances>. • 'Miscible' means 'capable of being mixed'; 'immisible' means 'incapable of being mixed'.

Soluble in water?

Sample D: Sample E: Sample A: cornflour flour salt

Test AUSTRALIAN CURRICULUM SCIENCE

soluble

Sample F: chalk

Soluble in water?

Iodine turns blue/ black.

soluble

Sample B: baking soda

soluble

Iodine Iodine turns blue/ turns blue/ black. black.

Soluble in water?

Sample A

Sample C: baking powder

Iodine remains yellow/ brown.

Soluble in water?

Turns iodine blue/black?

Gas produced

Sample B

Turns iodine blue/black?

Gas produced

Produces gas with vinegar?

No reaction

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IDENTIFICATION CHART

No Gas reaction produced

No reaction

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Page 57 Sample D Sample E Sample F

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• Make up the identification chart for students to compare their observations and make an identification.

Soluble produces white insoluble insoluble elastic solid.

• Collect all the equipment for the activity on page 57 including the six samples: (A) salt, (B) baking soda, (C) baking powder, (D) cornflour, (E) flour and (F) chalk.

Iodine remains yellow/ brown.

• Collect apparatus (or pictures of apparatus) used in the different separation techniques.

Sample C

Preparation

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Reaction with Reaction Reaction with water with iodine vinegar

Chemical sciences

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• Samples taken from anywhere within a homogeneous mixture will always have identical properties. Samples from different places within a heterogeneous mixture will have different properties as the proportions of component substances are not evenly distributed.

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What are mixtures and pure substances? – 1

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Each type of element is made up of only its own type of atom; for example: gold (Au) and carbon (C). All the known elements are listed in the periodic table. The position of each element in the table is based on its individual properties.

Compounds are made up of two or more different atoms joined together; for example, water (H2O) and carbon dioxide (CO2).

In a homogeneous mixture, which is called a solution, it is not possible to see the separate substances. For example, just by looking, could you tell the difference between a glass of pure water and one that contained a teaspoon of sugar or salt? Did you know that your stainless steel cutlery is not made of one single metal but a mixture of four different metals! Air is another example of a homogeneous mixture. It is made up of a number of gases, including nitrogen, oxygen and carbon dioxide.

In a heterogeneous mixture, the separate substances can be seen; for example: a mixture of instant coffee and sugar granules or the layers of oil and vinegar in a salad dressing. Cloudy liquids are heterogeneous mixtures called suspensions. Solids scattered throughout the liquid reflect the light, stopping it from passing through. Milk is an example of a heterogeneous mixture.

Au Au Au Au Au Au Au Au Au Au Au

H H

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Au Au Au Au Au Au Au Au Au Au Au gold

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H H

O H

water

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Many more mixtures exist in the world than pure substances, and scientists have discovered various ways to separate them based on the properties of their component parts.

Method

vinegar

salt solution

To separate:

oil

Property

salad dressing

Example

Evaporation

a soluble solid from a liquid

boiling point

salt from water

Distillation

a liquid from a soluble solid

boiling point

water from sea water

Fractional distillation

two miscible liquids

boiling point

water and vinegar

Decantation

two immiscible liquids

density

oil and water

Filtration

an insoluble solid from a liquid

solubility

dirty water

Chromatography

soluble substances

solubility

food colouring

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Chemical sciences

A mixture is a combination of two or more substances. Its properties depend on the proportion of each substance within it. For example, the freezing/melting and boiling/condensing points of a mixture occur over a range of temperatures because the values for each component of the mixture are different. Mixtures can be either homogeneous or heterogeneous.

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A pure substance is a solid, liquid or gas that can not be physically separated. It always has the same physical and chemical characteristics or properties; for example, pure water always freezes and melts at 0 ºC and boils and condenses at 100 ºC. The chemical composition (the number and type of atoms within a molecule) of a pure substance is always the same; for example, pure table salt is always composed of one atom of sodium (Na) to one atom of chlorine (Cl). There are two types of pure substances, elements and compounds.

What are mixtures and pure substances? – 2 Use the text on page 55 to answer the questions. 1. What am I? (a) My appearance is uniform but I am made up of different parts that can be physically separated. (b)

My appearance is uniform and I am made up of different parts that can not be physically separated.

(c)

My appearance is uniform and all my parts are exactly the same.

(d)

My appearance is not uniform. My different parts can be physically separated.

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2. Write the examples of each given in the text. (a)

An element:

(c)

A homogeneous mixture:

(d)

A heterogeneous mixture:

3. (a)

(b)

(b) A compound:

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What is the main difference between a pure substance and a mixture?

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4. Why is a suspension cloudy?

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5. The elements in the periodic table are grouped together by their 6. (a)

(b)

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If a salad dressing made with oil and vinegar is a heterogeneous mixture of two immiscible liquids, how would you describe a mixture of water and white vinegar?

Write the missing word. Miscible liquids can

together.

7. What separation method am I? I can be used to separate … (a)

two liquids that form a homogeneous mixture.

(b)

undissolved particles from a liquid.

(c)

a dissolved solid from a liquid. Chromatography is a separating method that is used extensively in biochemistry and medical science. Research to discover the name and nationality of the person who developed chromatography. What was he trying to do when the idea first came to him?

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Using properties to identify substances Similar looking substances can be identified by testing different properties and comparing them to the properties of known substances. You will be given a number of samples to test and then identify by using the chart provided by your teacher. You will need: • samples A, B, C, D, E and F • measuring jug • iodine Procedure

• six saucers

• six measuring spoon sets

• six stirrers

• two eye-droppers

• water

• vinegar

• a marker pen

• six saucers

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Perform each test and record and explain your observations in the table. Identify each sample by comparing your results with the identification chart. Reaction with vinegar

Reaction with iodine

Reaction with water

Measure one-quarter teaspoon of sample on to each saucer. Add two drops of vinegar to each.

Measure one-quarter teaspoon of sample on to each saucer. Add three drops of iodine to each.

Measure one tablespoon of sample into each glass. Add 200 mL of water to each and stir for 10 seconds.

Results

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Reaction with water

Reaction with iodine

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Reaction with vinegar

Test

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Identify each sample A

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Chemical sciences

Use the marker pen to label the glasses and saucers: A, B, C, D and E.

What are solvents and solutes? Content focus: Inquiry skills focus:

• Solubility is generally measured in grams per litre so the amount they add to make a saturated solution in 100 mL is multiplied by 10.

Solvents and solutes in solutions Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

• Determining the point of saturation at each temperature requires care and patience. With the cold and hot water solutions, students need to work relatively quickly to avoid too great a rise and loss in temperature of the solution. • Students compare their results with others and against recognised solubility values for Epsom salts.

r o e t s Bo r e p ok u S Answers

Background information

• When all the space has been filled, no more solute can be dissolved. This is a saturated solution.

• If more solute is added to a saturated solution, it will be visible. It will first be in suspension, making the solution look cloudy, and then as it settles at the bottom of the container. This is called precipitation. • If a saturated solution at simmering point is cooled rapidly, the excess solute molecules will quickly return to their solid structure and precipitate out of the solution. If it is cooled slowly, it takes more time for the solute to precipitate, so it is possible that at a lower temperature there is still more solute dissolved in the solvent. A solution in this state is called supersaturated.

• Print a list of the solubility values for magnesium sulphate (MgSO4 – epsom salts) for a range of temperatures.

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Solubility of MgSO4 at given temperature 22.0 g/L 28.2 g/L 33.7 g/L 38.9 g/L

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40 ºC 60 ºC 80 ºC

44.5 g/L 54.6 g/L 55.8 g/L

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• Collect all the materials listed on page 61.

0 ºC 10 ºC 20 ºC 30 ºC

1. (a) It is a homogeneous mixture of a solvent and one or more solutes dissolved in it. (b) It is broken down into tiny particles that are too small to see. These particles are evenly distributed within the solvent. 2. (b) It dissolves more solutes than any other solvent. 3. acetic acid 4. Soluble minerals from rocks dissolve in water as rivers runover and through them; soluble pollutants dissolve in rain and irrigation water and run off into rivers; chemicals are added in water treatment plants to kill bacteria. 5. (a) A solid solution of a solid solvent and a solid solute (b) The solid solvent and solute(s) are melted and mixed to form a homogeneous mixture, then cooled. 6. (a) silver (b) copper 7. Teacher check; expect: jewellery made from pure gold would damage easily as it is a soft metal. Because it is a rare metal, pure gold jewellery would be very expensive. 8. Nitrogen is the solvent in air because it is present in the greatest quantity. Science as a Human Endeavour question Use and influence of science • In osmosis, water passes through a barrier from a solution of higher water content to a solution of lower water content, trying to even out the two concentrations.

• A useful website is <http://www.chem4kids.com/files/matter_ solution.html>. Preparation

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• A solvent will keep dissolving a solute while there is still space between the solvent molecules to be filled. This is an unsaturated solution.

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• Remind students of the differences between homogeneous (clear, the same throughout) and heterogeneous (visible differences, nonuniform) solutions.

• In the investigation on page 61, students predict whether solubility increases or decreases with a rise in temperature. • To ensure an accurate result, students must take care with measuring and stirring, making sure not to lose any of their solute or solution. Epsom salts are used in preference to table salt as the difference in solubility at each temperature is greater.

• In jam making, fruit is heated with a concentrated sugar solution. Water from within the cells of any bacteria (high water content) that have survived the heating process passes through the cell walls of the bacteria into the concentrated sugar solution (low water content). This dehydrates the bacteria and prevents them from reproducing as they need water to survive. Page 61

• Students will find that solubility is proportional to temperature and so more salt will dissolve as the temperature of the solution increases. Comparing their solubility values to those on the prepared list will indicate the accuracy of the students’ experimental technique.

• Just below simmering point is used to ensure that no water is lost as steam. This would affect the solubility result.

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What are solvents and solutes? – 1 A solution is a homogeneous mixture in which one or more substances (solid, liquid or gas), dissolve in another. The substance that dissolves is called the solute. The substance that dissolves the solute is called the solvent. The solute does not disappear but it does become invisible because it is broken down into tiny particles that we can not see, and then evenly distributed throughout the solvent. In any solution of two or more substances, the substance that is present in the greatest quantity is the solvent and the others are the solute. This table shows some examples.

Solute salt (solid) acetic acid (liquid) carbon dioxide (gas)

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Solutes that do not dissolve in water may dissolve in other solvents, and vice versa. Examples of other solvents include ethanol (which is the alcohol used in perfume), turpentine (used in paints) and ethyl acetate (used in nail polish). You may think tap water is pure, but it contains soluble rock minerals that dissolve in river water as it runs over and through rocks. Soluble pollutants dissolve in rain and irrigation water, contaminating the environment; for example: fertilisers and pesticides from farms and gardens, industrial and household waste and sewage.

© R. I . C.Publ i cat i ons The water in your body (which makes up 70% ofr you) dissolves solutes such salt, oxygen, • f o rr ev i ew pu po ses on l yas• sugars and minerals, which are then transported around the body. Sweat, urine and tears are

In water treatment plants, chlorine and fluorine are added to the water to kill bacteria. Tests have shown that when fluorine is added to tap water, consumers are less likely to suffer dental decay.

common solutions produced in the body.

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In a solid solution, known as an alloy, the solute and solvent are both solids. They are heated together to form a homogeneous mixture and then cooled. In the table are some examples.

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• the gas/air mixture in a motor vehicle engine • the scent of perfume, air freshener and cleaning materials in the air • unpleasant smells from decaying organic matter in the air. R.I.C. Publications®

brass bronze steel

Solvent

Solute

copper copper iron

zinc tin carbon

o c . che e r o Gas Proportion t r s sup er Pure gold is 24 carats, nitrogen almost 78%

Air is a gas solution. It contains a mixture of gases in different proportions. Other gas solutions include:

Alloy

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Solutions can also be solids or gases.

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oxygen argon

almost 21% almost 1%

carbon dioxide and other gases

very small amounts

but the gold often used in jewellery is 18 carats. An 18-carat gold ring has 18 parts gold to 6 parts other metals. Gold is the solvent and the other metals (silver, copper, zinc) are the solutes.

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Solvent water water water

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Solution sea water vinegar soda water

Water dissolves more substances than any other solvent and it is known as the ‘universal solvent’. All forms of life absorb the solutes dissolved in water as it continues through its natural cycle.

What are solvents and solutes? – 2 Use the text on page 59 to answer the questions. 1. (a)

(b)

Using the words solvent and solute, explain what a solution is.

What happens to a solute when it dissolves in a solvent?

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2. Tick the box to indicate the correct ending to the statement? ‘Water is called the “universal solvent” because:

(b) it dissolves more solutes than any other solvent.’

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3. In a solution of 5 mL of ethanol and 20 mL of acetic acid, which is the solvent?

4. Write three ways in which solutes can be introduced to water. •

(b) How is an alloy made?

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(a) it dissolves all known solutes.’

Eighteen-carat gold contains four parts silver and two parts copper. Nine-carat gold contains two parts silver, 11 parts copper and two parts zinc.

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In each case, which metal is the solvent? (a)

18-carat gold:

(b)

9-carat gold:

7. Pure gold is a soft, rare metal. Give two reasons why you think jewellery is not made from pure, 24-carat gold. • • 8. In air, which gas is the solvent? Explain why.

The strong sugar solution used in jam making prevents the fruit from being attacked by bacteria because of a property known as osmosis, which was first observed by a French scientist in 1748. Research and present a brief description of how osmosis works in jam making. AUSTRALIAN CURRICULUM SCIENCE

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The effect of heating on solubility

Materials

Prediction

You are going to compare the solubility of epsom salts in water at three different temperatures: straight from the fridge, at room temperature, and at just below simmering point.

â&#x20AC;˘ epsom salts â&#x20AC;˘ small spoon â&#x20AC;˘ thermometer

â&#x20AC;˘ water â&#x20AC;˘ measuring jug â&#x20AC;˘ small saucepan

â&#x20AC;˘ digital kitchen scales â&#x20AC;˘ acrylic glass cup â&#x20AC;˘ cook top

â&#x20AC;˘ plastic pot â&#x20AC;˘ stirrer

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Record the temperature of the water: T1 = Â°C. Weigh the plastic pot and add 100 g epsom salts (from now, referred to as â&#x20AC;&#x2DC;saltâ&#x20AC;&#x2122;). Record the total weight of pot + salt: W1 = g.

Procedure

í˘˛ Add small quantities of salt from the pot to the water, stirring after each addition until it takes more stirring to get the salt to dissolve. Continue adding salt in tiny quantities until the solution starts to look cloudy. Leave for one minute. If there are no grains of salt at the bottom of the glass, continue adding salt, a few grains at a time, stirring after each addition and leaving for one minute. Stop adding salt when grains of salt precipitate out of solution. Record the weight of pot + remaining salt: W2 = g.

ÂŠ R. I . C.Publ i cat i ons í˘ł Leave the water to heat to room temperature, (20â&#x20AC;&#x201C;25 Â°C). â&#x20AC;˘ orr ev i ew pur p o eso nl yâ&#x20AC;˘ Stir thef solution and record its temperature: T2 =s Â°C.

Continue adding salt in tiny quantities as in Step 2 until precipitation is observed. Record the weight of pot + remaining salt: W3 = g.

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í˘´ Transfer the solution to a saucepan and heat until solution starts to simmer.

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Return solution to the glass and record its temperature: T3 = Â°C. Continue adding salt in tiny quantities as in Step 2 until precipitation is observed. Record the weight of pot + remaining salt: W4 = g.

Results

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Weight of epsom salts added to 100 mL water to make a saturated solution

At T1 =

Â°C At T2 =

W1 â&#x20AC;&#x201C; W2 = how many grams?

W1 â&#x20AC;&#x201C; W3 = how many grams?

Â°C At T3 =

Â°C

W1 â&#x20AC;&#x201C; W4 = how many grams?

Conclusion

Solubility of epsom salts (g/L)

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í˘ą Measure 100 mL of cold water (straight from the fridge) into the glass.

How is separation used in the real world?

Inquiry skills focus:

Answers

Application of separation in industrial processes

Page 64

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

1. Across: 2. osmosis, 6. decanting, 10. desalination, 11. evaporation Down: 1. distillation, 3. sediment, 4. contaminants, 5. centrifuge, 7. precipitate, 8. coagulate, 9. condenser 2. (a) density (b) change of state (c) size of molecules 3. Platelets clot the blood when it comes into contact with air. 4.

Background information

Salts and minerals removed by reverse osmosis.

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• There are many applications of the numerous separation techniques in our everyday lives and in industry. Many industrial processes (such as an oil refinery) use a number of techniques. Other applications use just one; e.g when a spin-drier spins, the water in wet clothes is forced out through small holes in the machine drum by using the same principle that applies to all centrifuging.

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Water filtered through fine mesh to remove remaining solids.

• Not all techniques fit every job. For example, decanting is only effective in separating a liquid from a solid or another (immiscible) liquid if the solid or the other liquid is dense enough to allow full decantation without contaminated. (e.g. sand in water rather than flour in water.)

Preparation

Suspended solids coagulate and precipitate, leaving a sediment.

• A useful website is <http://library.thinkquest.org/11430/research/ techniques.htm>.

• Collect all the materials required for the activity on page 65. Examples of test materials are kitchen paper, cottonwool balls, wood shavings, flour and cheesecloth.

Chemicals added to coagulate contaminant solids in suspension.

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• For the activity on page 65, discuss the reliability of the investigation; e.g. same weight of material and same time exposed to layer of oil. Do they think more or less oil, water or material is required? How could they test this? (By testing the same materials but with different groups using different quantities of material, oil or water. Then groups compare results.)

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The lessons Contaminated water goes in.

Chemical sciences

r o e t s Bo r e p ok u S Clean water comes out.

Content focus:

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• Students must take care pouring their oil mixture onto the surface of the salt water. If it is poured too quickly or from too great a height, it will sink.

• The best materials are those that have absorbed the greatest amount of oil. This is determined by subtracting 50 g (original weight of material) from the weight after 24 hours. This is because the weight measured immediately after testing will also include absorbed water. (This will have evaporated within 24 hours).

• Ensure that the weight of the plastic tubs are taken into account when weighing the oil contaminated test materials.

• In the analysis of results, students record the material that absorbed the greatest quantity of oil. All materials could be listed in order of descending absorbency. Students can also record observations such as the state of each material after being in the oil.

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How is separation used in the real world? – 1 As people have discovered things about our world, the information has been used to develop products and processes that help us with our daily lives. For example, ways to separate the different components of mixtures have been developed based on the knowledge of the properties of pure substances. Separating blood products

Extracting products from plants

Aromatherapy is a type of therapy that uses the essential oils from plants. The oils are separated from its plant material by steam distillation, which was developed with the knowledge of how materials change state with heating and cooling. Highpressure steam is passed through the plant material, forcing the globules of oil to burst open and then evaporate. The essential oil vapour and the steam are released into a watercooled condenser and then collected in a container. The oil and water separate naturally as the less dense oil rises to the top. The two layers can then be easily separated by decanting (or pouring off) the essential oil. The process is fairly simple but the product is very expensive because it takes a huge amount of plant material to make a small amount of oil!

Plasma (55%) White blood cells and platelets (<1%) Red blood cells (45%)

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Essential oil Water

Collection vessel

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Cooling water comes out. Cooling water goes in.

oil

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Still

Steam generator

Water treatment

A number of separation techniques are used to remove contaminants in water. A chemical is added to coagulate (or clump) suspended solid materials together. The clumps precipitate out of solution, forming a sediment on the bottom of the tank. The cleared water is then filtered through fine mesh to remove any remaining solid particles. Salts and minerals are removed by desalination. In some cases, reverse osmosis is used. During osmosis, the water passes through a filter from a low-solute solution to a high-solute solution. With reverse osmosis, pressure is applied to force the water from a high-solute solution to the low-solute solution. The solute molecules are too big to pass through the filter; as such, the concentration of solute (salts and minerals) on one side of the filter increases while on the other, solutefree water is produced. ®

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Steam

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Cold-water condenser

Normal osmosis Filter

Solution with more solute

Solution with less solute

Water Flow pressure

Reverse osmosis Filter

Solution with solute

Water with no solute Water Flow AUSTRALIAN CURRICULUM SCIENCE

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Any sample of blood is a mixture of four main components: • red cells carry oxygen to all parts of the body • white cells are always present in small quantities, but multiply when the body is fighting infection • platelets clot blood when it comes into contact with air. This stops blood from flowing continually when you get a cut • plasma is the transport medium for the other blood components. When blood is donated, each sample is separated into its different parts because most recipients will only need one part of the blood. This means more people can be helped by each blood donation. A machine called a centrifuge spins the blood sample, forcing the more dense red cells to separate from the plasma (which remains on top). The two layers can then be easily separated by decanting or pouring off the plasma. The plasma is then spun again, this time separating the platelets (which settle on the bottom).

How is separation used in the real world? – 2 Use the text on page 63 to answer the questions. 1. Solve the clues to complete the puzzle. Down

Across

1. Separating a substance from a liquid by vaporising and then condensing it. 3. Undissolved particles at the bottom of a solution. 4. Unwanted particles in a solution. 5. Machine that separates the parts of a liquid mixture by spinning. 7. To fall out of a solution. 8. Clump together. 9. Equipment for cooling a vapour and returning it to its liquid form.

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11.

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2. Movement of a liquid into a solution of high concentration. 6. Separating a liquid from a solid or an immiscible liquid. 10. Removal of salts and minerals. 11. The change from liquid to a vapour.

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2. Match each process to the property of substances that is used. (a)

centrifuging

(b)

steam distillation

(c)

reverse osmosis

•

change of state

•

size of molecules

•

density

3. Which component of blood prevents major blood loss when your body bleeds, and how does it do it?

4. Draw a flow diagram to show the separation processes described for water treatment. AUSTRALIAN CURRICULUM SCIENCE

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Cleaning up oil spills Large-scale oil spills are one of the major environmental hazards we face today. The effects of such a disaster can last for many years. Research scientists continue to search for the most effective way to clear up the oil. You are going to investigate six possible materials to use to extract oil from sea water.

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í˘ą Pour 500 mL of water into the baking dish, add one teaspoon of salt and stir.

í˘˛ In the plastic cup, make the crude oil by mixing 4 tablespoons of oil with two tablespoons of gravy powder. Mix thoroughly.

í˘ł Gently transfer the oil onto the surface of the salt water.

í˘´ Weigh 50 g of each test material and, in turn, lay each on the oil in the dish. Leave for one minute, then remove carefully with tweezers and place in a plastic tub to reweigh.

í˘ľ Leave each contaminated test material undisturbed for 24 hours, then reweigh again.

ÂŠ R. I . C.Publ i cat i ons Results â&#x20AC;˘f oWeight rr eafter vi e w pu r posesonl yâ&#x20AC;˘ Material testing Weight after 24 hours Weight of oil extracted

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í˘ś Record results and observations in the table.

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Analysis of results Which materials performed best? How do you know?

Evaluation How might this investigation be improved?

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Prediction Which materials do you think will perform best? You will need: â&#x20AC;˘ water â&#x20AC;˘ salt â&#x20AC;˘ vegetable oil â&#x20AC;˘ gravy powder â&#x20AC;˘ measuring jug â&#x20AC;˘ plastic cup â&#x20AC;˘ set of kitchen measuring spoons â&#x20AC;˘ stirrer â&#x20AC;˘ heat-resistant baking dish â&#x20AC;˘ selected materials to be tested for their â&#x20AC;&#x2DC;oil cleaningâ&#x20AC;&#x2122; potential â&#x20AC;˘ six plastic tubs â&#x20AC;˘ digital kitchen scales â&#x20AC;˘ tweezers â&#x20AC;˘ timer Procedure

How is separation used in food production? Science as a Human Endeavour unit:

Answers Use and influence of science

Page 68

Content focus:

Separation techniques in the food industry

Inquiry skills focus:

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

1. Some ingredients might need to be treated, improved or changed and some impurities might need to be removed. 2. Sometimes people are concerned about the safety of some of the ingredients and additives. 3. (a) Crystallisation separates a solute from a solution. (b) The part of milk left over after cheese production. (c) It has to be condensed by heating and evaporation. 4. distance, stick 5. (a) crystallisation (b) decantation (c) evaporation (d) decantation (e) chromatography (f) chromatography 6. Solids are allowed to settle to the bottom of a container and the liquid on top carefully poured off. Horizontally rotating centrifuges are used—solids are forced to one end of the cylinder where they settle and are compacted, then discharged by gravity. 7. Vacuum tanks lower the boiling point of the milk so it can be evaporated at a lower temperature, which protects it from being damaged.

• The separation and analysis of mixtures is a fundamental process in chemistry. In this unit, students will consider why it is important and necessary in the food and beverage industry and some of the ways in which it is done. • Students should realise that only the basic concepts underlining the four techniques have been described. In reality, very complex equipment is required and separation often involves not just one but a number of different separation techniques.

Page 69 1. 2. 3. 4.

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There should be different patterns for each coloured sweet. Answers will vary. Teacher check Teacher check. Factors that might have affected a fair test include the amount and strength of the dyes and the level of the water or the care with which it was added. 5. Teacher check. Difficulties may include: obtaining an accurate measurement given the small scale and determining where one colour starts and another ends. 6. Discussion could involve considering that not all coloured sweets look the same; for example, one brand may have a red that looks like orange and another’s red may look more pink. Also companies may buy their colours from different manufactures.

• Useful websites include: − <http://www.nordicsugar.com/industry/movies/movie-sugarcrystallisation/> − <http://www.ndep.us/Color-Writing> − <http://www.pbskids.org/zoom/activities/sci/ papertowelchromatogr.html>.

Preparation

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• Make a 1% solution of salt water by using 10 g salt for 1 litre of water and stirring well to ensure all the salt is dissolved for the experiment on page 69.

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Background information

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• Revise the terms solution (a liquid with a substance dissolved in it); solute (the substance that has been dissolved) and solvent (the liquid in which the substance has been dissolved). The lessons

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• The investigation on page 69 requires students to suspend the filter paper from a pencil over a glass. The length of the paper is a critical factor and may need some adjustment to ensure it almost touches the bottom of the glass. The water level is also critical. The bottom of the paper must be in the water and the dots of colour must be above it. • Small candy-covered sweets such as M&Ms™ or Skittles™ are suitable. Care should be taken to ensure the sweets are separated on the plate so there is no chance of the colours mixing. For this reason, a separate toothpick is required for each colour and only a drop of water used on each sweet. • Students work in groups of four to complete this investigation. They will benefit from opportunities to compare, contrast and discuss their results with other students who have used the same and different coloured sweets. AUSTRALIAN CURRICULUM SCIENCE

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How is separation used in food production? – 1 The foods we eat are made up of many different substances which sometimes need to be treated, improved or changed in some way, or have ingredients or impurities that need to be removed. Separation techniques play a very important part in food and beverage production because of these requirements. People might have safety concerns about the ingredients and additives used to improve a food’s appearance and taste or to preserve it, so scientists are often required to find out exactly what is in a food. To do this, they need to separate a mixture and isolate and identify each of its ingredients and to measure how much of each there is. Food separation techniques include the following.

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• Juice from sugar cane is boiled in pans with water. Pure sugar crystals develop when it cools, leaving any impurities in the water. A centrifuge is then used to spin and separate them from water.

• Whey, the part of milk left after cheese production, is heated and evaporated to condense it, then cooled and stirred in tanks to crystallise. Decanting takes place in a centrifuge and impurities are washed away with water. Whey is an ingredient in many foods, including ice-cream, cakes and infant formula.

• Oil is heated, stirred and cooled to form crystals. The mixture of crystals and liquids is then separated by filters.

Chromatography: This technique is used to separate a complex mixture or a solution into its various components. It works because some of the components of the mixture are able to stick to a surface better than others, while other parts spend more time moving. The distance each of the components moves can be measured and compared. Chromatography is often used to separate vitamins, analyse colourants, to determine sugar and cholesterol content, and to detect contaminants and pesticides in food.

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Decantation: This process is used to separate or draw off a liquid mixed with solids. Decanting can be done by simply allowing the solids to settle to the bottom of a container and then carefully pouring off the liquid from the top. This method is used with some olive oil, which is decanted in specially shaped containers. (The more widely used method of separating by filtration is less expensive, but more of the taste and flavour is retained when it is decanted.) Decanting is also used in the wine industry to ensure a wine is crystal clear and has its true colour. Horizontally rotating centrifuges are also used to decant liquids from solids, mainly in the dairy industry. In this process, solids are forced to one end of the cylinder. They then settle and are compacted, then discharged by gravity. Liquids are forced to the other end, where they are discharged by gravity or by pressure. The solids are often then decanted again.

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Evaporation: In this process, heat is used to turn liquid into gas so water or other liquids can be separated and removed from a mixture. Heat provides the energy for the molecules in the solvent to evaporate into the air, so the final product is a concentrated liquid. Evaporation is used in coffee production and in the pharmaceutical industry to make drugs more stable and easier to handle. Because milk is heat sensitive, vacuum tanks are used in the dairy industry to reduce air pressure, which lowers the boiling point of the milk. Evaporated and condensed milk (and other dehydrated milk products) have a much longer shelf life and are much easier and cheaper to transport. R.I.C. Publications®

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Crystallisation: This involves the formation of solid crystals from a solution. It is used to separate a dissolved solute from a solution. Crystallisation is used in the sugar, dairy and edible oil industries.

How is separation used in food production? – 2 Use the text on page 67 to complete the following. 1. Why is it sometimes necessary to separate the ingredients in food and drinks?

2. Explain why scientists might need to find out exactly what is in a particular food.

(b)

What is whey?

(c)

What has to be done to whey before it can be crystallised?

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What does crystallisation do?

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3. (a)

4. In chromatography, components of a substance can be compared by measuring the

a solid from a saturated solution?

(b)

sand from water?

(c)

liquid solutions?

(d)

liquid and solids?

(e)

vitamin ingredients?

(f)

complex mixtures?

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(a)

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they move because some of the components certain surfaces better than others.

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6. Describe two different ways liquids and solids can be decanted. •

•

7. Explain why vacuum tanks are used to separate some milk products.

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Using chromatography You are going to use chromatography to investigate how the dyes used in the coating of different coloured sweets move through paper. Prediction: You will need: â&#x20AC;˘ 4 sweets with different coloured coatings â&#x20AC;˘ 4 short glasses â&#x20AC;˘ 4 toothpicks â&#x20AC;˘ white coffee filters â&#x20AC;˘ plate â&#x20AC;˘ ruler Procedure

â&#x20AC;˘ salt water â&#x20AC;˘ 4 pencils â&#x20AC;˘ stapler â&#x20AC;˘ scissors pencil

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í˘ą Cut coffee filters into 4 long í˘ś After 1 minute, remove sweets and dip a toothpick into one colour.

í˘˛ Fold one end over and

í˘ł Make sure paper strip is slightly shorter than the depth of the glass.

Allow to dry, then add more of the same colour to each dot. Repeat process.

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Paper is barely touching.

Add a small amount of that dye on pencil dots one dot and repeat for other colours.

staple it to form a loop.

í˘´ Draw a pencil dot 2 cm from í˘š Put pencil through stapled flap and suspend paper one end of each strip.

over glass.

í˘ľ Put 4 drops of water on

plate and place a sweet on each. Results

Pour salt water carefully into glasses so just the end of paper is in the water.

Leave for 30 minutes, then remove paper and allow to dry

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Analysis

1. Were you able to see a different pattern for each coloured dye?

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Sweet colour Description

Yes

2. Did you see a colour present in more than one of the four dyes you used? Yes

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3. Were your predictions correct? Yes 4. Was this a fair test? Reflection

Yes No

Why?/Why not? How would you change it?

1. Would you be able to measure and compare distances moved by different colours? Yes No Why?/Why not?

2. (a)

Do you think you would get the same pattern of colours if you used a different brand of the same colour of sweets?

(b)

Yes

Explain your reasons and discuss in a small group.

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Chemical sciences

strips about 4 cm wide.

What are some separation methods used around the home? Content focus: Inquiry skills focus:

• Students choose five different dry solid ingredients to make their mixture. Provide a range of different-sized foods so they need to consider how to separate each of them. Suggestions: whole peppercorns, crushed peppercorns, rice, small pasta shapes, dried beans/peas, various cereals, salt crystals, edible cake decorations, dried herbs.

Identifying and comparing separation methods around the home Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

Answers Page 72

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• The separation methods described in the text require the physical or mechanical separation of substances using filtration devices or techniques.

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• Useful websites: − <http://www.5min.com/Video/How-to-SeparateEggs-297706540> (How to separate egg white from yolk.) − <http://www.ehow.co.uk/video_2329810_strain-chickennoodle-soup.html> (Straining soup to produce a broth.) − <http://video.aol.com/video/kitchen-basics-with-the-cia-siftflour/1990155505> (How and why flour is sifted.) • These two websites provide information about the history of vacuum cleaners: − <http://inventors.about.com/od/uvstartinventions/a/VacuumCleaners.htm> − <http://wanttoknowit.com/who-invented-the-vacuum-cleaner/>

Preparation

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• Organise a display of the devices mentioned in the text. • Students will need access to the internet or other resources to answer the research question on page 73.

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Page 73

After their design is made, students should predict how well they think each ingredient will be separated before commencing that part of the task. Students should work out a way of comparing the ingredients before using their separating system. The best method is by careful weighing, though some may count each type of ingredient. Some ingredients might still be stuck in the structure if the holes are too small, so the weight/ amount of specific ingredients will differ from before they started. Students should compare the features of each group’s design, identifying good and bad points.

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• Organise the equipment needed for the investigation on page 109. The lessons

• While discussing the text with the students, the teacher and/ or students can demonstrate how to use the devices or methods mentioned in the text.

• Students should work in small groups. Provide them with a variety of materials/equipment to use in their separation system. Suggestions: different-sized (including holes) colanders, sieves, strainers and spoons; tweezers; tongs; measuring cups; kitchen scales; bowls for mixing; coffee filter bags; muslin; cheesecloth; unused kitchen wipes; paper towels; trays for building design on; wooden skewers or scissors to cut holes. Ideally, they should make a sieve tower, with holes decreasing in size and a solid-base tray at the bottom. They could use various materials and poke small holes in it.

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1. They separate liquid from solid foods by the use of holes to drain. 2. Possible answers: Use half an eggshell/slotted spoon/spoon to scoop out the yolk. 3. (a) using a colander/pot lid/sieve to strain water from the vegetables (b) pouring the brewed tea through a tea strainer (c) using a hand-held/commercial juicer that has a device for catching the pips and pith (d) allowing the soup to cool and removing the fat that has risen to the top 4. Unsifted flour is not aerated, so the cake would not be as ‘light’. 5. Possible answers: bathroom basin, laundry basin, shower drain hole, bath drain hole 6. (a) Coffee filter papers separate the coffee grounds from entering the pouring tank. (b) Clothes dryer filters prevent lint from entering the motor. Science as a Human Endeavour question Use and influence of science Before vacuum cleaners, carpets were hung out over a wall or line and beaten with an object (like a piece of wood) to release as much dirt as possible. Vacuum cleaners are based on the principle of using an air pump to create a vacuum. This sucks up debris (such as dirt and hair) which is collected in a bag or container so it can be disposed of. (The suggested websites regarding vacuum cleaners could assist students to answer this question.)

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What are some separation methods used around the home? – 1 The kitchen is the best place to find examples of separation methods used at home. Preparing foods for eating and drinking often involves using separation techniques. A kitchen contains several devices to help separate substances from each other. These include slotted spoons, colanders, sieves, tongs and strainers.

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There are various methods of separating foods (such as vegetables or pasta) from the liquid in which they were cooked. The lid of the cooking pot used can be put on the top of the pot with a small gap left, then tipped over the sink to drain out the liquid. A plastic or metal colander that contains various sized holes can be used. Slotted spoons are useful to lift and drain a poached egg from the water it has been cooked in.

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Tea and coffee preparation can include separation methods. The cover of a tea bag acts like a strainer so only the liquid from the infused tea strains into the water in the cup and not the tea leaves in the bag. A tea strainer is used over a cup if the tea has been brewed in a tea pot. Percolated coffee requires coffee filter papers so only the coffee liquid collects in the pouring tank and not the coffee grounds. Coffee plungers and commercial coffee machines also have straining/filtering devices. Other filtering methods in the kitchen include sink strainers and dishwasher filters to prevent large food scraps from entering the drain; handheld juicers and juicing machines to separate juice, pips and pith from the fruit; and commercial water filters to extract chemicals from tap water. Handheld sifters are used to separate the grains of flour, which aerates the flour and gives cakes a lighter consistency.

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A method of separating oil or fat from a liquid in the process of making soup stock and gravies is to allow the mixture to cool and settle. As oil and fat are less dense than water, they will rise to the top. They can then be spooned off or soaked up with paper towels. Other examples of separation methods in the home include filters in vacuum cleaners to prevent dust that has been vacuumed from re-entering the room, and filters in clothes dryers that stop the lint from clothes from entering the motor and causing overheating (and possibly fire). Separation methods can also be observed outside a home. Gutter guards prevent leaves from clogging up drainpipes and drains. Skimmer boxes in swimming pools have filters to catch larger particles from the water. The water is then filtered by a device such as a sand filter, which prevents tiny impurities in the water from re-entering the pool. All these around-the-home methods of separating materials help to make the jobs we do easier and our lives safer and healthier. What other separation methods can you think of that are around your home? R.I.C. Publications®

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A common separation method used in the kitchen that does not need purpose-built device involves separating the yolk and white of a raw egg. Two hands, containers for each part of the egg and a surface with a firm edge are all that are needed. First, the egg is carefully cracked in half against the surface. Then, the half eggshell containing the raw egg is held over a container. The yolk is repeatedly tipped from one eggshell half into the other, allowing the runny egg white to fall into the container and separate from the yolk.

What are some separation methods used around the home? – 2 Use the text on page 71 to complete the following. 1. What do these three devices have in common?

slotted spoon

colander

sieve

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3. Describe one separation method you could use to do each of these chores. (a) Straining vegetables

(b) Making a pot of tea

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4. What would happen if unsifted flour was used to make a sponge cake?

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2. Imagine you are separating an egg white and yolk and a bit of egg yolk falls into the white. What could you do to separate that bit of yolk from the white?

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5. Other than the kitchen sink, list at least three places inside your home that have a filtering device to prevent large particles from entering a drain.

6. Rewrite these sentences so they are correct. (a)

Coffee filter papers separate the coffee liquid from entering the pouring tank.

(b)

Clothes dryer filters prevent clothes from entering the motor.

Vacuum cleaners are a device to separate dust and dirt from carpets and other surfaces. Research to find out how people cleaned carpets in the past and the basic principle behind how early and modern vacuum cleaners work. AUSTRALIAN CURRICULUM SCIENCE

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Mixed-up food investigation Task: In a small group, design a system for separating a mixture of solid foods. • You will be provided with equipment to choose from to use in your system and a selection of foods to choose from to make a mixture to separate. • Complete the table below.

What ingredients will you choose for the mixture?

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Designing your system

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How will you compare the ingredients before and after they are separated?

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How well were the foods separated?

What parts of your design worked well?

Evaluating your system

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Draw and label a sketch of your design, explaining how it works.

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What parts of your design need improving? • Compare your group’s design with other groups. R.I.C. Publications®

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Before you begin

What are the relative movements of the Earth, sun and moon? Content focus: Inquiry skills focus:

The lessons

Comparing the rotation and revolution of the Earth, the sun and the moon

• Pages 75 and 76 should be used together. A globe of the Earth would be useful to show rotation, along with a torch to represent the sun. The animations on the suggested websites will give students a 3-D view of the rotation and revolution of the sun, Earth and moon.

Planning and conducting Processing and analysing data and information Evaluating Communicating

• Students should choose from the suggested equipment/materials the teacher provides to make their models for page 77 or add their own suggestions.

r o e t s Bo r e p ok u S Answers

Background information

Page 76

1. Possible answers: Telescopes hadn’t been invented which helped astronomical discoveries/people saw the sun, moon, stars and so on 'move across the sky' from Earth so presumed they revolved around Earth and not the sun. 2. Galileo used a telescope to view sunspots that appeared to move across the face of the sun. Their motion proved the sun rotates. 3. (a) It means that different parts of the sun rotate at different speeds. (b) Because the sun is composed of gases and the Earth and the moon are composed (largely) of rock. 4.

• A solar year is the time taken for the Earth to make one complete revolution around the sun. It is measured from one equinox to the next (time of equal day and night). • A dwarf planet is a space body that is large enough to be rounded by its own gravity but not gravitationally dominant in its orbital area and is not a moon. A plutoid is a dwarf planet further from the sun than Neptune.

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• Ancient philosophers/astronomers assumed the sun, moon, stars and planets visible to the naked eye all revolved around the Earth each day, believing the Earth to be the centre of the universe. The invention and use of the telescope to view further into space and see more accurately saw this geocentric (Earth as centre) theory gradually change. Gallileo was the first person to use a refracting telescope to observe and identify astronomic discoveries.

Preparation

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Moon

24 hours (1 day)

27.3 days

Time to complete one rotation

≈ 25 days ≈ 31 days at poles

What does it orbit?

Milky Way Galaxy

Sun

Earth (and sun)

Orbital speed

780 000 km/h

107 000 km/h

3600 km/h

Time to complete one orbit

230 million years

365 days (and just under 6 hours)

27.3 days

5. It means that moon makes one rotation and revolution in the same length of time. Science as a Human Endeavour question Nature and development of science Students should discover he used trigonometric methods (an important advancement) rather than geometric methods in his calculations. Useful website: <www.famousscientists.org/al-battani/>

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• Reference books or the internet will need to be available for students to answer the final question on page 76.

Page 77

• Collect equipment needed for the modelling demonstration activities on page 77. Suggestions for sun, Earth and moon models: different sized polystyrene balls; balloons, newspapers and glue for papier mâché models; different sized balls, different sized round fruit. Axes: skewers, dowelling, rulers, straws. Torches for sun’s light. Swivel chairs for students to model rotation. Materials for making labels and charts. Digital camera or video equipment for photographs/filming of the demonstrations. Globe of Earth. Cellophane, cottonwool, crepe paper, cardboard and other suitable art materials to use in creating the surface of the sun, Earth and moon.

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Earth

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• Useful websites: − <http://suntrek.org/sun-as-a-star/suns-vital-statistics/does-sunrotate.shtml> (animation and written information about the sun’s differential rotation) − <http://www.fearofphysics.com/SunMoon/sunmoon1.html> (animation of Earth and moon rotating while revolving around the sun) − <http://www.youtube.com/watch?v=lkWyM-M8o0c> (Earth rotating and orbiting sun while sun orbits galaxy) − <http://www.youtube.com/watch?v=OZIB_leg75Q> (animation and written information of synchronous rotation of moon)

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Earth and space sciences

The aim of the activity is for students to show their understanding of what they have learnt on page 75 by using models, other props and themselves to demonstrate how each space body rotates and revolves. After the demonstration, the teacher and student audience can rate the performance (score out of 10) and suggest what they didn’t understand or could have been explained or demonstrated better.

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What are the relative movements of the Earth, sun and moon? – 1 In ancient times, people believed the Earth was the centre of the universe. They thought celestial bodies like the sun, moon and stars all orbited around Earth, which they believed was stationary in space. However, astronomical discoveries over time have proved that the sun is the centre of our solar system, which is just one in the vast Milky Way galaxy. The Earth and our moon, other planets and their moons, dwarf planets, plutoids, asteroids, meteors and other space bodies all orbit the sun in our solar system—not the Earth. We know the Earth and our moon, and other planets and their moons rotate on their axis while orbiting the sun. But did you know that the sun also rotates and is in orbit?

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In contrast with the sun, Earth takes 24 hours or one day to rotate once on its axis. Earth’s rotation means that each part of the planet faces the sun for varying amounts of time each day, resulting in day and night. As the Earth rotates in an anticlockwise direction, the sun ‘rises’ in the east and ‘sets’ in the west. It appears to move across the sky but it is actually the Earth’s rotation causing this phenomenon. As Earth rotates, it is also orbiting in an elliptical path around the sun at approximately 107 000 km/h. Earth takes 365 days and just under six hours to orbit the sun. This measurement is rounded to 365 days and called a year. The extra hours, minutes and seconds are added up every four years to make a leap year, when an extra day is added to the month of February.

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Our moon makes one rotation on its axis every 27.3 days. This is also the time it takes to orbit Earth which it does at about 3600 km/h. Because the moon’s rotation and revolution are essentially the same, only one side of it ever faces Earth. This is called ‘synchronous rotation’. The moon orbits the Earth as both are orbiting the sun.

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Moon

Sun

Earth

All celestial bodies in space are constantly moving. Even our galaxy, the Milky Way, is gradually moving toward our nearest galaxy, Andromeda—and they are both moving towards the Virgo cluster of galaxies. Nothing stays still! R.I.C. Publications®

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Earth and space sciences

Teac he r

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Nearly 400 years ago, Italian astronomer, Galileo Galilei, was the first to observe (with the aid of a telescope) sunspots on the surface of the sun. These are magnetic storms that can be seen as dark areas, as they have a cooler temperature than the surrounding atmosphere. The motion of the sunspots proved the sun rotates, as they appear to travel across its face. It has also been discovered that the sun’s rotation is quite different from the Earth’s. Unlike our rocky planet and our moon, the sun is entirely composed of constantly exploding gases, mainly hydrogen and helium. This results in it not having a single rotation speed like Earth—different parts of it rotate at different speeds. This is called ‘differential rotation’. The sun completes one rotation at its equator approximately every 25 days and about every 31 days at its poles. The sun also orbits the Milky Way in an almost circular path at a speed of around 780 000 km/h. It takes about 230 million years to complete one revolution.

What are the relative movements of the Earth, sun and moon? – 2 Use the text on page 75 to complete the following. 1. Why do you think people in ancient times thought the moon, stars and other space bodies orbited the Earth and not the sun?

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3. (a)

(b)

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Teac he r

2. Explain how it was discovered that the sun rotated.

What is the meaning of ‘differential rotation’?

Why does the sun have differential rotation and not Earth or our moon?

4. Complete the table with facts.

Earth

Time to complete one rotation

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What does it orbit? Orbital speed

Time to complete one orbit

Moon

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Sun

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Earth and space sciences

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5. Explain the term ‘synchronous rotation’.

Research to find out about how Al Battani, an astronomer, astrologer and mathematician who lived in the 10th century, calculated the length of the solar year. AUSTRALIAN CURRICULUM SCIENCE

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Modelling rotation and revolution 1. Work in a group to plan how to make models of the sun, Earth and moon to use in demonstrations to show how each rotates and revolves (orbits) in space. Make notes and draw diagrams in the table below. Sun

Earth

Moon

What materials will you use to make each space body? Consider the following: • relative sizes

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• how to show each axis

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Notes about specific features of each space body’s orbit

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Notes about specific features of each space body’s rotation

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2. Work together to build your models. 3. Now plan the part each group member will play in the demonstrations. Work out what each person will display, how they will handle the model, where and how they will move and what they will say. Practise your demonstrations and perform for the class. 4. Rate your demonstration as given by your audience. 1 2 3 4 5 6 7 8 9 10 Suggest improvements, if needed, on the back of this sheet. R.I.C. Publications®

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Earth and space sciences

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• how to show surface of each; e.g. gaseous sun, ocean/continents on Earth, moon’s craters

Why do seasons occur on Earth? Content focus:

Inquiry skills focus:

− Why do some animals change the thickness or colour of their coats according to the season?

Earth experiences seasons due to its axial tilt Seasonal changes affect living things

− How do different seasons affect humans’ clothing choices/food preferences/outdoor or indoor activities?

Planning and conducting Processing and analysing data and information Communicating

− What effect does a specific season have on the household/school electricity or gas bill? − How do people keep warm/cool in winter/summer? Why are many animal young born in spring?

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− How do the seasons affect farming practices?

Background information

− Why do deciduous trees lose their leaves in autumn? How else do plants adapt according to the season?

− it is tilted on its axis

− What are some health and safety aspects to consider during different seasons? (hayfever, increase in colds/influenza in winter, UV rays in summer, preventing sunstroke in hot weather, safety aspects with use of heating devices in cooler months, importance of keeping hydrated in hot weather)

− consequently, different places on Earth receive direct rays from the sun at different times of the year

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• As explained in the text, the distance from the sun during the year is a common misconception as to why Earth has seasons. Earth’s elliptical path is not elongated—it is almost a circle. In summary, Earth experiences seasons because:

Answers

− the position of the Northern and Southern Hemispheres in relation to the sun result in different seasons.

Page 80

1. (a) The degree to which Earth is tilted on its axis. (b) perihelion, closest distance Earth is from sun (c) aphelion, furthest distance Earth from sun 2. (a) false (b) false (c) true (d) false 3.

• There are two dates given in the text for the solstices and equinoxes. The dates these phenomena fall depends on the shift of the calendar. • These videos both demonstrate how Earth’s tilt causes the seasons:

Preparation • A globe of the Earth on a tilted axis would be useful in modelling how the tilt causes the seasons, along with a torch to represent the sun. Display a world map showing latitudinal and longitudinal lines.

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Earth and space sciences

− <http://www.youtube.com/watch?v=DuiQvPLWziQ>

• Students will need access to resources such as computers, digital camera, reference books and charts, and other materials to plan, prepare and present their information for the activity on page 81. The lessons

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Northern Hemisphere

Southern Hemisphere

summer solstice

winter solstice

summer solstice

winter solstice

20/21 June

21/22 Dec.

20/21 June

vernal equinox

autumnal equinox

vernal equinox

autumnal equinox

20/21 Mar.

22/23 Sept.

20/21 Mar.

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− <http://www.videojug.com/film/why-does-the-earth-haveseasons>

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4. Teacher check 5. Because the Earth’s tilt makes the areas of high latitudes at each pole face toward the sun in summer, resulting in continuous daylight at that solstice. 6. Teacher check 7. Because the sun is almost or directly overhead, the temperature does not change dramatically.

• If a globe is available, place a marker such as a blob of clay on the place where the students live. As the Earth (globe) is rotated on its axis and revolved around the sun (torch), stop the clay bob at each ‘season’ to show what is happening according to whether it is facing more or less directly towards the sun. The websites above also provide a 3-D experience.

Page 81

• Revise/Teach the significance of latitude and longitude and, on a world map, identify significant latitude lines relating to the seasons.

Science as a Human Endeavour question Use and influence of science Teacher check

• Hold a class discussion about how seasonal changes affect living things so students can focus on an aspect of the topic to investigate and present to the class. They could present a general report or choose a specific area. Questions that can be discussed and further investigated could include: − Why do/Which animals hibernate in harsh winter climates? − Why do/Which animals migrate in different seasons? AUSTRALIAN CURRICULUM SCIENCE

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Why do seasons occur on Earth? – 1 Earth revolves around the sun in a slightly elliptical orbit. At the closest point of its journey around the sun, called the ‘perihelion’, Earth is approximately 147 000 000 km from the sun. At its ‘aphelion’, the point furthest from the sun, it is about 152 000 000 km. Many people believe that Earth has seasons because of this 5 000 000 km difference in the distance from the sun during the year. They think summer occurs when Earth is at its closest to the sun and winter when it is at its furthest. Although it seems an enormous distance, 5 000 000 kilometres is relatively small considering the total distance. Earth’s distance from the sun is not the cause of the seasons.

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Northern Hemisphere

Southern Hemisphere

Dec. – Feb. Summer south of the equator, winter north of the equator. The sun shines directly on the Southern Hemisphere and indirectly on the Northern Hemisphere.

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This chart explains when and why we experience winter and summer in the Northern and Southern Hemispheres. (Note: The sun and Earth are not drawn to scale.)

Mar. – May

Autumn south of the equator, spring north of the equator. The sun shines equally on the Southern and Northern Hemispheres.

There are two days each year when the Earth is tilted either directly at or away from the sun, causing it to reach its most southern and northern extremes. These are the summer and winter solstices when we experience the longest (most hours of daylight) and the shortest (least hours of daylight) days of the year.

June – Aug.

Winter south of the equator, summer north of the equator. The sun shines directly on the Northern Hemisphere and indirectly on the Southern Hemisphere.

Sept. – Nov.

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Spring south of the equator,

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autumn north of the equator. Halfway between each solstice, there is The sun shines equally on a day when Earth’s axis is tilted exactly the Southern and Northern Hemispheres. midway between the two extremes. This day has the same hours of daylight and darkness in both Hemispheres. This occurs twice a year and these days are called the vernal (spring) and autumnal equinoxes (depending on the Hemisphere). ‘Equinox’ is Latin for ‘equal day and night’.

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Each year, the dates of the solstices are 20 or 21 June and 21 or 22 December. The dates of the equinoxes are 20 or 21 March and 22 or 23 September. Whether they are summer or winter solstices and vernal or autumnal equinoxes depends on the Hemisphere. How high the sun appears in the sky and how long it remains above the horizon during the day is dependent on the latitude as well as the season. For example, the sun does not set on the day of the summer solstice at the high latitudes of the North and South Poles—24 hours of sunlight is experienced. Earth’s tilt makes each Pole face towards the sun in summer, keeping that area in sunlight as Earth rotates. The opposite happens at both poles at winter solstice—the sun does not rise at all as the Poles are tilted away from the sun, resulting in 24 hours of darkness! In tropical and subtropical regions, the sun is almost or directly overhead for most of the year. These areas do not experience four seasons. The temperature does not change dramatically— but the amount of rainfall can. Wet and dry seasons can be identified instead. R.I.C. Publications®

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Earth and space sciences

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Earth rotates on its axis as it orbits the sun, with its axis always pointing in the same direction.

The cause is the Earth’s axial tilt. Earth does not rotate vertically. It is tilted 23.5° on its axis—an imaginary line drawn through the centre of Earth from the North Pole to the South Pole. Because of the axial tilt, different parts of our planet are more directly facing the sun at different times of the year.

Why do seasons occur on Earth? – 2 Use the text on page 79 to complete the following. 1. What is the significance of these measurements? (a)

23.5°

(b)

147 000 000 km

(c)

152 000 000 km

2. Answer true or false.

(b)

Earth’s distance from the sun causes the seasons.

(c)

Earth’s axial tilt causes the seasons.

(d)

The longest day of the year occurs at the winter solstice.

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Earth rotates vertically.

3. Complete the table with the correct dates. Northern Hemisphere

summer solstice

Southern Hemisphere

winter solstice

summer solstice

winter solstice

autumnal equinox

vernal equinox

autumnal equinox

Favourite season:

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Sun’s rays:

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(a)

5. Why doesn’t the sun set at the North or South Pole on the summer solstice?

6. (a)

(b)

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Would you prefer to be in Antarctica around 21 June or 21 December?

Explain your answer.

7. Why aren’t there four seasons in tropical regions?

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How do seasonal changes affect living things? The seasons have an impact on human, animal and plant behaviour. After a class discussion, you and a partner will plan, research and write a report about how seasonal changes affect people, animals and/or plants. Use the headings in the table to help. Research topic

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What do we already know?

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What information do we need to find out?

(What questions do we need to answer?)

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What illustrations, photographs, diagrams, tables, graphs, spreadsheets etc. will we need?

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What websites, resources, equipment etc. will we need?

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(A general topic about impact on humans, animals and plants? Or one specific area?)

Why do phases of the moon occur? Content focus: Inquiry skills focus:

− What pattern, if any, are they noticing about the moon’s position in the sky? Is the moon larger or smaller when it is rising or setting, compared with when it is high in the sky? (It appears larger as it rises and sets; this is an optical illusion in relation to Earth’s horizon.)

Phases of the moon Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

• Students could use the media (TV, newspaper) or go to a website to find out when the moon actually rises and sets during the month of observation.

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Background information

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• The moon rotates once on its own axis at approximately the same time as it orbits once around Earth. This is known as ‘synchronous rotation’. Because of this, only one side of the moon ever faces Earth.

1. (a) and (b) should be ticked 2. They occur because the sun’s rays reflect off the moon at different angles as it orbits Earth. 3. (a) getting bigger (b) getting smaller (c) convex or bulging 4. (a) waxing crescent, first quarter, waxing gibbous (b) waning gibbous, last quarter, waning crescent 5. (a) During a new moon we see no moon as it is between Earth and the sun. During a full moon we see all the moon as Earth is between the moon and the sun. (b) During the waxing stages, more of the moon becomes visible. During the waning stages, less of the moon can be seen. (c) During the first quarter, the right half of the moon is visible. During the last quarter, the left side is visible. 6. It can best be observed during the first and last quarter as it is at an angle of 90º and high enough in the sky. 7. Possible answer: ‘When does a blue moon occur?’

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• The moon can be seen for different lengths of time during most days of the lunar month because the light it reflects from the sun is bright enough to penetrate the scattered blue light of the sky. It must also be high enough in the sky. • In the southern hemisphere, the moon waxes and wanes from the left. In the northern hemisphere, this occurs from the right. • These two websites show a short video of the phases of the moon: − <http://www.childrensuniversity.manchester.ac.uk/interactives/ science/earthandbeyond/phases.asp> (This site also provides a quiz.)

− <http://www.youtube.com/watch?v=nXseTWTZlks>

Preparation

Page 85

The lessons

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• A large colour chart or photograph from a reference book of the moon’s phases would be useful to display while covering this topic.

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• This is an educational ‘hip-hop’ presentation of the phases of the moon: <http://www.youtube.com/watch?v=AQRNzepe4wI>

Students should compare and discuss their observations with other class members. • Were any observations recorded on the same day different? Were they taken at the same time? (If not, the moon could be located in a different place in the sky due to Earth’s rotation.)

• The models of Earth, the sun and the moon and other props used for the demonstration activity on page 77 could again be used by the students to demonstrate how the phases of the moon occur.

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• Did clouds obscure their view of the moon? (They could check throughout the day if clouds are present.)

• Students could work individually, in pairs or in a small group on the observation activity on page 85. They should predict where and what they think the moon will look like before they check each night/day. Explain that the first observation they make of the moon on the first day of the chosen calendar month will not necessarily be of a new or full moon. • Before they begin, ask them to identify the following: − Which side of the moon first becomes visible in the waxing stage? (left) − How does this compare with the waning stage? (moves to the right) − In what phases is the moon more easily seen at night? In the morning? During the day?

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Why do phases of the moon occur? – 1 Since ancient times, people have been fascinated by the moon, with many cultures creating interesting myths about this largest and brightest object in our night sky. Probably the most intriguing aspect of the moon is its changing appearance. Over a month, it grows larger until it becomes a glowing, silvery-white disc. Then the opposite happens—it decreases in size until it forms a curved sliver, before completely disappearing. This takes about 29.5 days or one lunar month. This endless cycle continues. The moon is Earth’s only natural satellite. In the same way Earth orbits the sun, the moon orbits Earth. The moon is held in place by Earth’s gravitational pull. Like Earth, the moon does not emit light of its own—we are able to see it because it reflects the sun’s light. The different shapes of the moon we see from Earth during a lunar month are called the phases of the moon. They occur because the sun’s rays reflect off the moon at different angles as it orbits Earth and as Earth revolves around the sun.

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Each of the eight phases of the moon has a name to describe its shape.

The moon as seen from Earth

first quarter crescent waxing

First quarter: When the moon has completed about a quarter of its orbit around Earth, the left half of the side of the moon we can see is visible. This is called the ‘first quarter’.

gibbous waxing

full moon

new moon

Earth

gibbous waning

crescent waning

last quarter

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Waxing gibbous: When more than a quarter of the moon is visible, the moon is in the ‘waxing gibbous’ phase. ‘Gibbous’ means ‘convex’ or ‘bulging’.

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Full moon: When the sun and moon are aligned with Earth in the middle, the side of the moon facing Earth is fully lit. This is called a ‘full moon’. The moon is halfway through its cycle. Waning gibbous: As the moon continues to orbit Earth, the lit portion again becomes less and the moon appears to ‘wane’ (get smaller). This is called the ‘waning gibbous’. Last quarter: When the right half of the side of the moon we can see is visible, it is said to be in its ‘last quarter’. Waning crescent: The final phase is when only a thin crescent of the moon appears. This is the ‘waning crescent’ phase. After this phase, the moon begins its cycle again. Throughout the lunar month, the moon can be observed mostly in the night sky. It is most easily seen during the day near the first and last quarter. This is because it is at an angle of 90° away from the sun and high enough to be visible in the sky. Occasionally, there are two full moons in a calendar month instead of just one. The second full moon is called a ‘blue moon’. This occurs about every 2.7 years—hence the saying, ‘once in a blue moon’. R.I.C. Publications®

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Waxing crescent: As more of the sunlit side of the moon becomes visible, the moon appears to ‘wax’ (get bigger). We see a sliver or crescent of the moon. This is called the ‘waxing crescent’.

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New moon: When the moon is between Earth and the sun, the side of the moon facing Earth is dark. This is called a ‘new moon’.

Why do phases of the moon occur? – 2 Use the text on page 83 to answer the questions. 1. Tick the facts that are true for Earth AND the moon. Both: (a)

emit no light of their own.

(b) orbit a space object.

(c)

appear to change shape.

(d) are held in space by Earth’s gravity.

2. Why do phases of the moon occur?

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3. Explain each of these terms. waxing

(b)

waning

(c)

gibbous

4. Which phases fall in the: (a)

(a)

a new and full moon.

(b)

a waxing and waning moon.

(c)

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(b)

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waxing stage between the new moon and the full moon?

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(a)

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a first and last quarter moon.

6. Describe when and why the moon can best be observed during the day.

7. Write a question for this answer.

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Answer: 2.7 years

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Observing the moon’s phases 1. Observe the moon each night (or day if visible) from the first day of a calendar month. 2. In each box in the table, record the date and time of viewing, where you viewed it from (home or school), sketch the shape of the moon, name the phase and describe its position in the sky. 3. Compare your observations with others in the class.

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Mon.

Tues.

Wed.

Thurs.

Fri.

Sat.

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Month:

What are solar and lunar eclipses? Content focus: Inquiry skills focus:

• Ask students why they think it is safe to view a lunar eclipse. (Only reflected sunlight is seen, not the sun itself.)

Solar and lunar eclipses Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• Students could work in a small group to construct the pinhole projector. The longer the box, the larger the pinhole image will be. The size of the image will be about 1/100th the length of the box. Answers Page 88

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1. Answers should indicate that an eclipse occurs when a celestial body casts a shadow on another celestial body as the former blocks the sun’s light. 2. In a solar eclipse, the moon moves between the sun and Earth. In a lunar eclipse, Earth’s shadow fall on the moon. 3. Students should draw the moon partly in Earth’s umbra and partly in the penumbra. 4. (a) annular (b) partial (c) umbra (d) total (e) full, new 5. The light (and heat) of the sun is blocked. 6. The diagram shows how Earth’s and the moon’s orbits are slightly tilted in respect to each other. Eclipses can only occur when the sun, Earth and the moon are in line at the intersection of these two planes. Science as a Human Endeavour question Nature and development of science Teacher check

• Lunar eclipses can occur up to three times a year and are visible over an entire Hemisphere.

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• Solar eclipses can occur at least two and no more than five times a year. They always occur two weeks before or after a lunar eclipse. • There are three stages to a total solar eclipse:

− Bailey’s beads: small bursts of light that appear 15 seconds before and after totality. − Diamond ring: large burst of light appearing a few seconds before and after totality. − Totality: the moon’s disc hides the sun but we can see the sun’s corona which is not normally visible.

• Both these websites show an animation of lunar and solar eclipses.

Page 89

− <http://www.fearofphysics.com/SunMoon/sunmoon1.html> (see also link at bottom of page)

1.–2. Teacher check 3.–4. An inverted image of the sun (a round spot of light) should be seen. 5. Light from the sun travels in straight lines through the pinhole, giving a reversed image where it falls on the white paper. 6. Possible problems/solutions: having difficulty pointing the box to project an image onto the paper/use the shadow of the box on the ground to move the box so the sides are not casting a shadow on the ground; the pinhole may be too small or too large, making the image too hard to see/replace foil with smaller pinhole

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• On this website, an astronomer explains a lunar and solar eclipse. <http://www.youtube.com/watch?v=wHxcWSiD_4E> Preparation

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− <http://www.videojug.com/film/what-is-an-eclipse>

• Organise the materials needed to construct the pinhole projector on page 89. Long postal boxes and cylinders are a useful resource. The lessons

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• Along with the text on page 87, use some of the suggested websites that show animations of lunar and solar eclipses to help students understand how they occur.

• The activity on page 89 is best completed to coincide with a solar eclipse. (Alternatively, they can construct one and simply use the sun to practise viewing with the projector, in preparation for an actual eclipse.) Visit the following websites to view a list of when each occurs in the coming years: <http://eclipse.gsfc.nasa.gov/SEdecade/SEdecade2011.html> <http://eclipse.gsfc.nasa.gov/lunar.html> • Discuss the dangers of viewing solar eclipses before students commence the activity. (The only time it can be viewed with the naked eye is during the totality stage of a total solar eclipse; however, this practice is best not undertaken as it is can be hard to tell when totality finishes and partial commences.)

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What are solar and lunar eclipses? – 1 As ‘solar’ means ‘relating to the sun’ and ‘lunar’ means ‘relating to the moon’, the title above refers to an eclipse of the sun and one of the moon. But what is an ‘eclipse’? Eclipse comes from a Greek word meaning ‘cease to exist’. An eclipse occurs when a planet or moon comes between a source of light, like the sun, and another celestial body. A shadow is cast on this celestial body, causing it to partly or wholly ‘disappear’ for as short as a few minutes to as long as two or three hours. From Earth, we experience a solar eclipse when the moon moves between Earth and the sun, blocking the sun’s light on Earth; or a lunar eclipse, when the moon lies in Earth’s shadow.

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Lunar eclipse

Solar eclipse

Earth

umbra

Sun

Earth

penumbra

umbra

moon moon

penumbra

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penumbra

Sun

Note: In the diagrams above, ‘umbra’ refers to the dark, inner shadow, and ‘penumbra’ to the faint, outer shadow.

There are three main types of solar eclipse: partial, total or annular.

– In a total eclipse, as shown in the diagram above, the moon appears to cover the entire solar disc. Such eclipses are only visible from a small area on Earth. Totality, when the solar disc is entirely covered, lasts for less than 10 minutes. During this time, stars can be seen in the darkened sky and there can be a noticeable drop in temperature. The partial phase of a total eclipse lasts for about an hour.

There are two main types of lunar eclipse: partial and total.

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– An annular eclipse occurs when the moon does not cover the entire solar disc but leaves an ‘annular’ or ring of brightness. This type of eclipse happens when the sun is closest to Earth, making the solar disc appear larger, and the moon is furthest from Earth, making the moon appear smaller. – A partial eclipse occurs when only part of the moon lies in Earth’s umbra.

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– A total eclipse occurs when the moon lies completely in Earth’s umbra, as in the diagram above. This lasts for approximately one hour. Solar eclipses occur only during a new moon while lunar eclipses happen only during a full moon. But why don’t they happen every time there is a new or full moon? Eclipses can only be experienced when the sun, Earth and moon are in line. Because the plane of the moon’s and Earth’s orbits are slightly tilted in New moon solar eclipse respect to each other, eclipses can Line of Earth only take place when the sun, Earth nodes Sun and moon are near the intersection of these two planes. There can be from two to seven eclipses in a calendar year. moon

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– A partial eclipse occurs when the moon covers part of the solar disc (sun). The viewer is in the penumbral part of the moon’s shadow.

What are solar and lunar eclipses? – 2 Use the text on page 87 to answer the questions. 1. In your own words, describe what an eclipse is and how it occurs.

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2. What is the difference between a solar and a lunar eclipse?

r o e t s Bo r e p ok u S Lunar eclipse Earth

penumbra

Sun umbra penumbra

4. Choose the correct word to complete each sentence.

The moon covers part of the solar disc in a

solar eclipse.

during a total lunar eclipse.

(c)

The moon lies completely in Earth’s

(d)

All of the solar disc is darkened by the moon’s shadow during a solar eclipse.

(e)

Lunar eclipses occur only during a

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(b)

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3. On this diagram, draw the location of the moon during a partial lunar eclipse.

moon while solar eclipses

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5. Why does the temperature drop during totality in a total solar eclipse?

6. Explain what the diagram at the bottom of page 87 is illustrating.

View this website and others you find to discover what ancient civilisations believed about lunar and solar eclipses: <http://starryskies.com/The_sky/events/lunar-2003/eclipse7.html> AUSTRALIAN CURRICULUM SCIENCE

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Observing a solar eclipse Unlike a lunar eclipse, a solar eclipse cannot be viewed with the naked eye—this includes viewing it with binoculars, a telescope or even polaroid™ sunglasses. The concentrated sunlight can cause permanent eye damage or blindness. Special solar filters can be attached to the lenses of optical equipment for safe viewing. A simple, safe and inexpensive way to view a solar eclipse is by using a pinhole projector. Follow the steps to construct a pinhole projector and answer the questions. 1. Equipment:

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• cardboard box or tube about 2 m in length (2 or 3 shorter boxes can be taped together as long as the ends in the middle boxes are removed to allow light through) • piece of aluminium foil

•

craft knife or sharp scissors

• tape

•

piece of white paper

2. Steps:

(a)

Cut a square or rectangular hole from one end of box.

(b)

Tape foil over hole.

(c)

Use pin to poke tiny hole in centre of foil.

(d)

Cut viewing hole on side at other end of box (see diagram).

(e)

Tape white paper inside box at end near viewing hole.

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•

If you were incorrect, describe what you saw.

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(b)

Were you correct?

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4. (a)

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5. Give an explanation for what you saw.

6. List any problems you encountered and suggestions for solving them. Problem(s)

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Solution(s)

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3. Predict what you will see on paper before pointing pinhole end towards sun and looking through viewing hole at white paper. (Note: Do not look through pinhole at sun.)

How have advances in telescopes and space probes helped astronomers? Content focus:

Inquiry skills focus:

• Students could work in pairs or a small group to write the report on page 93, comparing the ideas the three astronomers formulated in developing their heliocentric models of the solar system. Some useful websites:

How advances in telescopic equipment have provided new evidence for astronomers Questioning and predicting Planning and conducting Processing and analysing data and information Communicating

Background information

− <http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_ level2/copernicus.html> (brief Copernicus biography) − <http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_ level2/galileo.html> (brief Galileo biography)

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− <http://outreach.atnf.csiro.au/education/senior/astrophysics/ galileo.html> (Galileo and the telescope) − <http://www.learn-persian.com/english/Khayyam_Omar.php> (information about Khayyam) − <http://www.physicsoftheuniverse.com/dates.html> (chronological list of important astronomical discoveries)

• Space exploration involving crewed missions is limited. People need all their life support systems provided—food, water and oxygen. At present, the length of time it would take just to reach Mars would be several months, and to the nearest star—1000s of years.

− <http://www.bluffton.edu/~bergerd/NSC_111/science3.html> (models of the solar system)

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• The first telescope was invented by Hans Lippersely in 1608 but Galileo was the first to use one for astronomical observations.

− <http://www.polaris.iastate.edu/EveningStar/Unit2/unit2_sub2. htm> (Copernican sun-centred model) − <http://www.polaris.iastate.edu/EveningStar/Unit2/unit2_sub1. htm> (Ptolemic Earth-centred model) Answers

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1. People in early civilisations used their naked eye while modern astronomers use space telescopes and space probes. 2. (a) A refracting telescope uses lenses to bend light while a reflecting one uses mirrors to reflect light. (b) Reflecting. They don’t have all the problems associated with colour and shape distortion. 3. His discovery helped disprove the theory that Earth was the centre of the universe. 4. If used from outer space above Earth’s atmosphere, the problems of cloudy weather, pollution and atmospheric blurring do not interfere with observations. 5. existence of exoplanets, existence of water on Mars, Pluto is a dwarf planet 6. Teacher check 7. Possible answers: (a) When was the first space probe launched? (b) Since when have great advances in space observation been made?/When was the first telescope invented?

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• Useful websites: − <http://hubblesite.org/hubble_discoveries/> (information about Hubble telescope discoveries) − <http://kepler.nasa.gov/multimedia/Interactives/ HowKeplerDiscoversPlanetsElementary/flash.cfm> (a simple animation and a comprehensive interactive explaining how the Kepler spacecraft can detect planets orbiting distant stars) − <http://kepler.nasa.gov/multimedia/Interactives/ keplerFlashAdvDiscovery/flash.cfm> − <http://webbtelescope.org/webb_telescope/> (information about the James Webb telescope, which will be the successor to the Hubble Space Telescope) − <http://www.ehow.com/about_5113072_important-were-madereflecting-telescope.html> (explains difference between both kinds of telescopes and information about specific discoveries) − <http://www.universetoday.com/13573/why-pluto-is-no-longera-planet/> − <http://www.nasa.gov/missions/current/index.html> (current NASA missions into outer space)

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• Reference material showing a chart of the solar system; the Milky Way; early and modern telescopes, space telescopes and spaceprobes; and information about the astronomers mentioned in the text on pages 91 and 93 would be useful to assist students in understanding the text on page 91 and writing the report on page 93.

Page 93 Teacher check

The lessons • Ensure students understand any terms mentioned in the text; e.g. 'celestial', 'hypothesise', 'refracting', 'reflecting', 'dwarf planet'. Use the relevant listed websites to assist.

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How have advances in telescopes and space probes helped astronomers? – 1 beyond Earth’s atmosphere has enabled astronomers to discover much more about the universe. Earth’s atmosphere makes viewing celestial objects difficult. Cloudy weather, pollution and atmospheric ‘blurring’ of images present problems. The inability of some kinds of light such as microwaves, X-rays and gamma rays to pass through the atmosphere is another problem. A solution is to install telescopes on satellites and launch them into space. Space telescopes have various cameras and electronics that allow images and information to be collected from deep into space that are sent back to Earth for astronomers to examine.

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Most space telescopes are uncrewed and in orbit around Earth. Some of these include the Hubble Space Telescope, the Fermi Gamma Ray Large Area Space Telescope and the Kepler Space Telescope. A recent discovery by Kepler is the existence of exoplanets— planets outside our solar system. A combination of Earth-based and space-based telescopes provided evidence for astronomers to reclassify Pluto, once the most distant and ninth planet in our solar system, to dwarf planet status.

In 1610, Italian astronomer, Galileo Galilei, became the first person to look at celestial bodies using a refracting telescope. He made many important observations, including the discovery of Jupiter’s four brightest moons. This eventually helped to disprove the theory of the time that Earth was the centre of the universe and everything orbited around it and not the sun. Galileo reasoned if Jupiter had moons orbiting it and not Earth, then Earth’s moon could orbit it as both revolved around the sun.

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The first spaceprobe launched was Sputnik 1 in 1957. It carried some instruments and transmitters, unsophisticated compared with today’s. Its purpose was to study the atmosphere. Some modern space probes are programmed to land on a planet or moon to survey and collect samples of soil etc. This information is relayed back to Earth. For example, Mars was previously thought to be a dry, barren planet. However, the Phoenix Mars Lander spaceprobe’s robotic arm scooped up a soil sample containing water!

In 1668, (Sir) Isaac Newton constructed the first reflecting telescope. It used mirrors to reflect light rather than lenses to refract (bend) it. This removed some of the problems with colour and shape distortion like the refracting telescope used by Galileo. Since then, astronomical observations with telescopes have greatly accelerated, particularly in recent times. Modern telescopes are still based on the reflecting telescope developed by Newton and are used in observatories on Earth and in space probes that orbit beyond Earth’s atmosphere or travel into outer space.

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Several one-way missions into outer space are currently underway. The New Horizons spacecraft is bound for Pluto and other celestial bodies towards the edge of our solar system. It will take more than 10 years to reach its destination!

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Astronomy is not a recent science—it has been practised for thousands of years. Early civilisations used their observations of the positions and motions of celestial bodies like the stars to keep track of time, plant their crops, and, among other things, navigate on land and at sea. But their observations were restricted to what they could see with the naked eye. The invention of the telescope in the early 17th century allowed people to view distant objects in space more clearly and in greater detail. Since then, advances in telescopes and space exploration by craft such as space probes, have provided astronomers with continual new data to advance our knowledge of the universe. It has enabled astronomers to rely on scientific evidence and not just hypothesise.

How have advances in telescopes and space probes helped astronomers? – 2 Use the text on page 91 to complete the following. 1. Summarise the main differences between the manner in which people in early civilisations and modern-day astronomers observed the universe.

(b)

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What is the difference between a refracting and a reflecting telescope?

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2. (a)

Which type are modern telescopes and what advantages does this type have?

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3. What was the significance of Galileo’s discovery of Jupiter’s four brightest moons?

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5. Modern Earth-based or space-based telescopes have provided astronomers with new evidence about space. Explain three recent things they have discovered. •

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6. Why do you think the New Horizons spacecraft is uncrewed?

7. Write a question for these answers. (a)

1957

(b)

early 17th century

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Comparing models of the solar system In ancient times, people believed Earth was the centre of the universe, and the moon, planets and stars revolved around it. This is known as a geocentric model. Astronomer, Claudius Ptolemy, developed a model of this in the 1st Century. This belief was held for more than 1000 years until astronomers such as Copernicus, Khayyam and Galileo challenged it with models of the sun at the centre.

Saturn Jupiter Mars Sun Venus Mercury moon

Earth

1. Research to find out how they developed theories of a heliocentric (sun-centred) model of the solar system. Use the table below to assist you.

Why did he disagree with the geocentric model?

Diagrams to assist in the explanation

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he try to prove his heliocentric model?

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How did people react to his theory?

2. Work out what websites, nonfiction material and other resources you will need and plan how you will present your report. R.I.C. Publications®

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Details about early life

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What are Earth’s resources? Content focus:

Answers

Natural and synthetic resources

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Renewable and non-renewable resources Inquiry skills focus:

1. A renewable natural resource is a resource found in nature that is unlikely to run out or, once used, can be replenished or reproduced at approximately the same rate at which it is being used. 2. water: R, coal: NR, oil: NR, wind: R, ice block: R, sunlight: R, natural gas: NR 3. Three of the following: • trees: trees need to be replaced once they are cut down. Whole forests take a very long time to replace. • fish: people need to ensure enough fish are left to reproduce and replenish stocks. • oxygen: people have to ensure enough plants (especially trees) are left to provide oxygen. • fresh water: needs to be kept free of pollution. • Plants and animals: plant and animals species should not be over harvested or hunted. 4. Trees produce oxygen which is used by humans for respiration. 5. Coal, oil and natural gas 6. Answers should indicate that relying on non-renewable resources, which will one day run out, to provide power means that we will eventually have no power to run cars, lights and appliances. 7. (b) mismanagement by humans 8. Teacher check Science as a Human endeavour question Nature and development of science The Aral Sea was formerly one of the four largest lakes in the world. It has been shrinking since the 1960s after the rivers that fed it were diverted by a Soviet Union cotton irrigation scheme. By 2007, it had declined to 10% of its original size. Fish species have disappeared, virtually destroying the region’s fishing industry, bringing unemployment and economic hardship. Toxic dust-salt blown onto surrounding farmland is harming crops, the water is becoming hazardous to drink and those people who remain in the area have lost their main livelihood.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

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• Everything comes from something, and that ’something’ is Earth’s natural resources. Natural resources are found in the natural environment and are used by all living organisms to sustain and improve life.

• Earth’s resources can be classified as being either renewable or nonrenewable: − renewable resources are materials or living organisms found in the natural environment that either will not run out or can be replaced at approximately the same rate as they are being used.

Preparation

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• Useful websites: − <http://www.neok12.com/quiz/NATRES01> − <http://library.thinkquest.org/C004179/polyester.htm> (has a description of some common textiles)

• Students will need access to the internet to answer the ‘Science as a human endeavour’ question on page 96, and for page 97.

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• Collect clothing items made from different materials or textiles, clearly displayed on the care label, for the experiment on page 97. The lessons

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1.–2. Teacher check. Cotton, silk, wool, leather and linen (flax) are natural (and renewable), most other fabrics are synthesised and extracted from coal, petroleum and natural gas by-products (non-renewable). 3. Teacher check 4. (a)–(b) Teacher check <http://www.npra.org/ourIndustry/ petrochemicalFacts/> has a downloadable chart of items made using petrochemicals. Students might speculate that other resources, or ways or using nonrenewable resources, would have to be found to make those products should the resource be depleted.

• Read page 95 with the students and check for understanding. Terms such as 'respiration', 'minerals' (naturally occurring substances, usually inorganic, formed through geological processes that have specific chemical and physical properties), 'replenished' and 'conserved' may need discussion or explanation.

• The aim of the activity on page 97 is for the students to investigate the source of materials used to make everyday clothing items. After the activity, discuss the students’ findings. Ask how the results might have been different if the study was done in a different country (with a different climate or style of clothing), or if a different sample of clothes had been provided.

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− non-renewable resources cannot be replaced after they are used, or are used much faster than they can be replaced. There is a limited supply of these resources and once we have used them, they will be gone.

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What are Earth’s resources? – 1 Earth is the only known planet that sustains life, largely because it is home to a wide range of resources—soil, air, water, plants, sunlight, minerals and other substances. All living things use Earth’s resources to meet their needs and wants—without them, there would be no life.

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The resources on Earth that are used by living things as they occur naturally in the environment are called natural resources. People use Earth’s natural resources in many different ways—oxygen is used for respiration; animals are used to provide meat and clothing; diamonds and gold for jewellery; plants for food; clothing, housing and furniture; and oil, gas and coal are used to make plastic products and clothing, or are burnt to create power. When natural resources are transformed by people into something else for use, a synthetic resource is created. Items you use every day, such as pencils, computers and furniture are synthesised resources. Although they are made by humans, they can only be created using natural resources.

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Some resources, however, are unlikely to run out or, once used, can be replaced. Resources that can be replenished or reproduced at approximately the same rate at which they are being used are called renewable resources. These resources can be replaced by natural ecological cycles or careful human management. The only way we can lose these resources is if we are not careful about how we use them. Renewable resources include:

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Fish: Fish reproduce themselves naturally. They can also be farmed. As the human population grows, there is a greater demand for fish. People need to ensure enough fish are left to reproduce and replenish stocks.

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Trees: Trees reproduce themselves naturally. A tree that is cut down for timber to make furniture can be replaced by another tree or a seed planted in its place. However, if an entire forest of 200-year-old trees is cleared, it will take hundreds of years for the forest to regenerate.

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Sunlight: The sun shines constantly, providing light, heat and energy.

Oxygen and wind: Oxygen is produced naturally by plants. However, as more forests are cleared for wood and residential and farming land, we have to ensure enough plants (especially trees) are left to provide oxygen, which is essential to life. Fresh water: This is delivered as part of Earth’s water cycle. However, fresh water cannot be used by living things if it is polluted. People need to ensure fresh water is kept clean. Plants and animals: These are renewable resources as long as they are adequately conserved. Farmers plant, grow and harvest then replace crops every year, and manage the numbers of livestock. However, over-harvesting or uncontrolled hunting can deplete some species to very low numbers or drive them to extinction.

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Oil, gas, minerals and coal are natural resources that form within the Earth over millions of years. People mine them and use such large amounts of these resources, so quickly, that they are being consumed much faster than they can form. It is essentially impossible for usable amounts of these resources to be replaced once they have been used because they form so slowly—in other words, once the present supplies of these resources are used up, they will be gone forever. Any resource which, once used, cannot be replaced or restored, is called a non-renewable resource.

What are Earth’s resources? – 2 Use the text on page 95 to complete the following. 1. Write a definition of renewable natural resources.

2. Write ‘R’ for renewable or ‘NR’ for not renewable next to each resource. (a)

water

(e)

ice blocks

(b) coal

(c)

oil

(d) wind

(f)

(g)

natural gas

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•

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3. Write three renewable resources that need to be carefully managed by people to ensure they stay renewable, and how we can do this.

4. Explain the relationship among these resources: oxygen, humans and trees.

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(a)

6. What could be a possible future problem with relying heavily on non-renewable resources to provide power to run cars, appliances and lights?

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5. Name three non-renewable resources that are used to create power.

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7. Underline the best ending for this sentence.

‘Some renewable resources could become non-renewable due to ... (a)

natural resources.’

(b) mismanagement by humans.’

8. Write one advantage of using a renewable natural resource instead of a non-renewable natural resource to create products or power.

Use the internet to read about the Aral Sea in Central Asia, and how overuse of a resource like water in one place can mean deprivation in another. AUSTRALIAN CURRICULUM SCIENCE

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What is the source of this resource? Labels on clothing help us to be aware of which resources are being used in their production. 1. Find items of clothing (including shoes) with a care or textile label. Use the information on the label and the internet or textbooks to complete the chart. One section has been completed as an example. Natural or synthetic Natural resource used material to make this material

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natural

silk (silkworms)

satin (polyester)

synthetic

oil (petrochemicals)

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blouse

Materials used

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2. Write the name of three natural resources you identified, then, next to each, write whether they are renewable or non-renewable. (a) (b) (c)

3. Which materials were more commonly used—synthetic or natural? 4. Write the name of one non-renewable natural resource you identified. (a)

What else is this resource used to make?

(b)

On the back of this sheet, write a possible consequence of this resource being depleted.

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Clothing item

How long do resources take to regenerate? Content focus: Inquiry skills focus:

Answers

Timescales for the regeneration of natural resources

Page 100 1. sunlight, fresh water, tree, hardwood forest, coal 2. sunlight, wind and tides 3. The remains of plants and animals that lived hundreds of millions of years ago were buried in sand and silt and became fossilised. With exposure to heat and pressure in the earth’s crust over millions of years, these remains formed oil. 4. Natural regeneration happens naturally from seeds or parts of trees that were on the land previously, while artificial regeneration involves humans planting seeds or seedlings. 5. (a) slower than their regeneration rate. 6. pollution 7. Answers will vary but should indicate that if humans deplete stocks of fish, populations of other animal species that rely on fish for food will suffer. 8. Answers will vary significantly, but should mention that an oldgrowth forest takes thousands of years to form, contains many plant and animal species, and is important for producing oxygen and removing carbon dioxide from the air. If an entire forest of old trees is completely cut down, animals leave or die, the soil can erode away and ecosystems change, meaning new plants may not be able to grow as well, possibly resulting in less clean, oxygenated air, for thousands of years until it can regenerate. Science as a human endeavour question Nature and development of science To find out how to better manage natural resources, an environmental scientist might find and reduce pollution and other environmental problems, design ways to recycle resources better, find ways to protect plant and animal resources using science, maths, computers and hightech measuring tools and instruments.

Planning and conducting Processing and analysing data and information Communicating

Background information

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• Most of Earth’s natural resources are able to regenerate, but at very different rates.

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• Some, like radioactive metallic elements, oil, natural gas and coal take so long to form that their stores are considered finite—once we have used them, they will be gone. Some resources, such as living organisms, regenerate on a faster scale. Other resources, such as sunlight, regenerate faster than they can be replaced. • Connected with the ability of resources to regenerate are the amounts, rates and ways they are used by humans. If a resource is used faster than it can regenerate, reserves will dwindle. If resources are polluted or the environments in which they can form are destroyed, this too will affect the capacity for regeneration.

• Environmental sustainability involves maintaining a balance between nature’s capacity to regenerate and the effect of the actions of humans. Many people believe we consume and destroy certain resources faster than the Earth’s capacity to regenerate.

• Useful website: − <http://explore.ecb.org/videos/VLC_ media?P1=VLC138&REFERER=OTHER> (has a range of images of different resources that can be downloaded)

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Students will need to decide if they are in the affirmative or negative, and research to help them write a speech supporting their decision. Teachers can grade the students based on the content of their speech, or on both the content and how it is delivered, depending on which outcomes teachers would like to focus on achieving through this lesson. Encourage the students to identify where scientific discoveries have been used to support to claims from both sides of the debate.

Preparation

• Students will need access to the internet to complete the activity on page 101. The lessons

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• Biomass (organic matter used as a source of energy) will be covered in the following section (pages 102–105).

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• Ensure the students understand terms such as 'depletion', 'recycling', 'organisms', 'microorganism', 'old-growth forest', 'purify' and 'pollution'. If possible, complete pages 94–97 before doing this set of pages. • The aim of the activity on page 101 is for students to research different points of view on the topic of coal, gas and oil supplies running out. The term ‘fossil fuels’ has not been used as it will be explored in the next section in this book.

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How long do resources take to regenerate? – 1 Earth’s resources regenerate (form again or are replenished by the environment) at different rates. Some regenerate continuously, while others take millions of years. Some resources, such as coal, oil and natural gas 300-400 million years ago 50-100 million years ago take so long to form naturally in the environment that use of these resources causes them to be used up much faster than they can form. These resources are believed to have formed as a result of fossilised remains of dead plants and animals being exposed to heat and pressure in the Earth’s crust over millions of years. Soil, especially topsoil (the top layer of nutrient-rich soil that sustains healthy plant life), can take thousands of years Sand & Silt Sand & Silt to regenerate if lost through erosion or poor farming Rock practices. So, although these resources do regenerate, Oil & gas deposits Plant & animal remains they take so long to do so that they are usually considered to be non-renewable. Some of these resources, however, can be regenerated through recycling. While bauxite ore, from which aluminium is made, is a non-renewable resource, aluminium itself can be continuously recycled and reused. OCEAN

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Other resources, especially living organisms, are able to regenerate within a relatively shorter length of time. Different organisms regenerate at different rates; for example, a tiny microorganism can reproduce to make millions more in a number of hours, while an adult killer whale (10–13 years old) can usually only have one baby every 3–10 years (after a 17-month gestation). Other animals, such as fish, regenerate relatively quickly, but are also used by humans in very large amounts. If people take fish quicker than the fish can reproduce, then the amounts of fish will decline. Some fish stocks have already been reduced to such low levels that they could become extinct.

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Plants regenerate at different rates. A tree takes longer to grow than a small flowering plant, and a hardwood tree (such as eucalyptus) takes longer to grow than a softwood tree (such as pine). Regeneration of trees can be natural (from seed, sprouts, or root parts of trees on or formerly on the land), or artificial (from seed or seedlings planted by humans). If an entire forest of trees is completely cut down, animals leave or die, the soil can erode away and ecosystems change, meaning new plants may not be able to grow as well. Oldgrowth forests, home to many animals and plants, evolve over a long period of time and could take hundreds of years to regenerate.

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Fresh water is an essential natural resource that is delivered as part of the hydrologic (water) cycle. In tropical areas, fresh water in the form of rain can regenerate quite quickly. In other areas, it takes longer. If fresh groundwater is used up and no rain falls, there can be, for a period, a lack of fresh water available. The regeneration of fresh water is also affected by pollution. Polluted water can take a long time to purify naturally. Sunlight, tides and wind are resources that can renew constantly, without depletion from human use. They regenerate faster than they can be used. Oxygen is continuously produced by plants, which also remove carbon dioxide from the air, so the constant regeneration of oxygen and breathable air is dependent on the presence of plants. Resources can only regenerate at certain rates. Humans increasingly consume some resources faster than they can regenerate. We need to carefully manage, or conserve, these resources, because excessive use could lead to their depletion or inability to regenerate. R.I.C. Publications®

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OCEAN

How long do resources take to regenerate? – 2 Use the text on page 99 to complete the following. 1. Write these resources in order from fastest to regenerate to slowest to regenerate. coal

fresh water

tree

hardwood forest

sunlight

2. Which three resources regenerate constantly, regardless of human action?

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3. Describe how oil forms, using both the illustration and text on page 99.

4. What is the difference between natural and artificial regeneration of trees?

5. Underline the correct ending for the following sentence:

(b)

(c)

faster than their regeneration rate.’

‘To ensure renewable resources are not depleted, people need to use them ... (a)

slower than their regeneration rate.’

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7. What effect could humans depleting stocks of fish have on other species that rely on fish for survival?

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6. Name one factor that can affect the regeneration of fresh water.

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8. Imagine you come across a group of people protesting against an old-growth forest being cleared. They have a banner with the words ‘Trees are Earth’s lungs – Destroying forests destroys our planet’. What do the protesters mean by these words? Include the words ‘oxygen’, ‘regenerate’, ‘ecosystem’, ‘plants’ and ‘animals’ in your answer.

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Oil, coal and gas will run out ... won’t they? No-one knows exactly how much oil, coal and gas is in the Earth. Most of the coal deposits have not even been found yet. Developments in technology mean we rely less on these resources anyway. There will be enough to last thousands of years. All fossil fuels are finite—the deposits that exist cannot be replenished once they have been used. As the world population grows and people consume these resources more, they will run out—probably in our lifetime.

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Plan a short debate speech (3–5 minutes) in the affirmative or negative of the topic below, using the guide provided. Use the internet to research your information. Then, on a separate sheet of paper, write out your speech to present to the class.

• I believe that this statement is true/false (circle as appropriate).

Plan

1. My first point is (I think that...):

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3. The evidence comes from:

4. My second point is (I think that):

5. I think this because:

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6. The evidence comes from:

(If you have more points, list them on a separate sheet of paper.) 7. In conclusion:

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The topic for debate is ‘That oil, gas and coal resources will run out in our lifetime’.

Which resources are used for energy? Content focus: Inquiry skills focus:

The lessons

Renewable and non-renewable energy sources

• Ask the students to list some of the things they do each day that use energy. Next to each, write what kind of energy is used (e.g petrol, electricity, batteries, gas etc). Then ask the students if they know how electricity or car fuels are created, and discuss their answers. Read page 103 together and discuss.

Questioning and predicting Planning and conducting Processing and analysing data and information Communicating

• The aim of the activity on page 105 is for the students to further investigate a renewable source of energy.

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Background information

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• At present, coal, oil and natural gas (fossil fuels) make up the bulk of the world’s energy sources. These are non-renewable; they formed in the earth over millions of years and are unable to be replenished. Fossil fuels, when used to create electricity and power internal combustion engines, are also a major contributor to pollution. • With global demand for energy growing, and the future prospect of the total depletion of non-renewable resources, the need to adopt alternative energy sources is also growing. Using renewable resources, which give energy continuously and do not deplete with careful use, provide a sustainable alternative to non-renewable resources.

Page 104

• Ethanol has not been mentioned in this section. Is it a renewable source of energy which can be used as transportation fuel.

Preparation

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• Useful websites: − <http://www.agso.gov.au/renewable/> (provides maps of operational renewable energy generators across Australia) − <http://energyquest.ca.gov/index.html> (has good information about the different energy sources and how they are used) − < http://www.ga.gov.au/energy/basics.html> (has information about resources used for energy in Australia) − <http://www.youtube.com/watch?v=SeXG8K5_UvU> (video showing how coal is used to create electricity)

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1. (a) Two of the following: nuclear, oil, coal or natural gas. (b) 1/7 (c) biomass and hydro-electric (d) Non-renewable sources of energy are used far more than renewable sources. (e) Students’ drawings will differ but should reflect decreased use of the non-renewable sources and increased use of renewable sources. Some students might include wave or tidal energy sources in the pie chart. 2. The production of electricity using biomass and coal both require the burning of the resource to create steam to power turbines. 3. Burning fossil fuels to create electricity uses up a non-renewable resource and also creates pollution. 4. Answers should indicate that as most electricity is created by using non-renewable resources such as coal, natural gas and oil, using less electricity means less of these resources are used and hence supplies are better conserved. 5. Two of the following: to heat water, to heat homes, to cook, to create electricity. Science as a Human endeavour question Use and influence of science The Rance Tidal Power Station is a tidal power station on the estuary of the Rance River, in Brittany, France. A dam catches the moving tidal water, using the flow created by the height differential between the water levels to power 24 turbines using hydropower technologies and thus generate electricity.

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• Energy is required for the different types of work we do every day. Heat energy from burning fuels like wood, coal, petrol and natural gas is widely used for cooking and other purposes. Different forms of energy are converted into electrical energy to operate computers, microwave ovens, television, vehicles and machines.

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Teacher check

• It is intended that students complete this set of pages after completing pages 98–101. If not, ensure the students understand the concepts of renewable and non-renewable resources. • Students will need access to the internet, presentation software (if desired) and printers to complete page 105.

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Which resources are used for energy? – 1 Each day, people rely on energy to preserve or cook food, get to places, warm or cool their homes, see when it gets dark and for entertainment. This energy comes from the use of a number of resources, which are either renewable (can be used repeatedly without being used up) or non-renewable (cannot be replaced or remade once used).

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At present, the main resources used for energy are coal, oil and natural gas. These non-renewable resources are called fossil fuels because they formed millions of years ago from layers of fossilised living organisms. They are used mainly to create electricity, the principal energy used in homes, businesses and factories. Fossil fuels are burnt in power plants to create heat which is used to boil water inside a boiler. The fastmoving steam is piped to a turbine, a kind of engine, making it spin. The turbine is connected to a generator that creates electricity. Burning fossil fuels in this way creates pollution. Natural gas is also used for heating and cooking, and oil is used to make fuel (e.g petroleum and jet fuel) for many forms of transport.

Dams can be built to trap water and create hydro-electricity. Water flowing at speed through specially built tunnels in a dam wall is used to turn turbines. The moving water tides and the energy contained in waves can be used to power a turbine. Geothermal power plants use steam or hot water heated naturally below the earth’s surface to power turbines without needing to burn fuel. Biomass energy comes from burning sawdust, agricultural waste, wood chips, some rubbish and manures at high temperatures to once again boil water and create steam.

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Renewable energy sources can also be used to produce electrical power using turbines. Wind has been used for many centuries to turn windmills to pump water from wells or turn large grinding stones to grind grain. Wind can also be used to create electricity using wind turbines. The blades of the turbine are attached to shafts which turn a generator to make electricity.

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Sunlight can be used to create electricity or to heat water without the use of turbines. Solar panels (photovoltaic cells) are used to convert the sun’s energy into electricity. Some households and businesses use solar panels on their roofs to power lights and appliances. Solar hot water systems work in different ways to heat water using sunlight. Solar energy can also be stored in batteries to light gardens or roadside signs at night. Solar energy, like wind, geothermal and hydro-energy, produces no pollution. Non-renewable resources, so heavily relied on for fuel and electricity, will eventually run out. Alternative cost-effective ways to produce energy, including the use of renewable sources of energy, need to be further developed to ensure energy supplies in the future. R.I.C. Publications®

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Radioactive fuel is another non-renewable resource used to create electricity. Inside nuclear power plants, the nuclei of atoms of certain metallic elements, such as naturally-occurring radioactive uranium ore, are split to release large amounts of energy. This energy is used to heat water to create electricity. Some ships and submarines are powered by nuclear energy. Nuclear energy does not create pollution; however, it does produce radioactive waste, which remains dangerous until it naturally decays (thousands of years). There is no way of safely disposing of this waste, so it is buried and contained to prevent leaks which could kill living organisms and contaminate environments.

Which resources are used for energy? – 2

Biomass

Geothermal

Use the text on page 103 to complete the answers.

Wind and solar Hydro-electric

1. Look at the pie chart opposite showing global sources of energy. (a)

Write two non-renewable energy sources. •

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About what fraction of energy sources are renewable? • 1/2 • 1/7 • 1/20

(c)

Which two renewable energy sources provide the world with the most energy?

Coal

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(b)

How does the use of renewable sources for energy compare to the use of non-renewable sources?

Draw what you think a pie chart of global energy sources might look like in 100 years.

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3. What are two disadvantages of burning fossil fuels to create power?

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Oil

Natural gas

•

(d)

Nuclear

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4. How can using less electricity help to conserve non-renewable resource supplies?

5. List two ways gas is used as an energy source. • • Use the internet to find out what kind of energy is used to create electricity at the Rance Power Station in France, and how this energy source is used to do so. AUSTRALIAN CURRICULUM SCIENCE

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Energy alternatives for the future With a partner or in a small group, choose and research one renewable energy source (solar, wind, geothermal, biomass or hydropower). Prepare a presentation, using graphs, keys, diagrams or models where possible. Make notes under the headings below to include in your presentation. How this technology works (how the energy is harnessed)

The ways this energy source can be used

•

Places this energy source currently is being used

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•

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•

If the technology is widely accepted or used, and why or why not this is so

•

Other information of relevance/interest

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Any environmental or cost issues associated with the collection or use of this energy source

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•

What is the water cycle? Content focus: Inquiry skills focus:

• After discussion, students write the amount of soil and water to be used in their tub in the ‘Equipment’ section on page 109. Ensure each group seals the tub correctly and has the same size marble.

Studying Earth’s water cycle in terms of changes of state Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• When complete, add a card/sticker labelled A, B, C etc. on each still for identification. Each group places their still in a different location, with each having a different level of exposure to sunlight; e.g. under a tree, in full sun on concrete/bitumen, in full sun on grass, in full sun on a wall/storage shed roof, in an undercover area.

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• There is no ‘beginning’ or ‘end’ to the water cycle—depending on the temperature, water can change states among liquid, solid and gas during any part of the cycle.

• Students should all remove the cup from their still at the same time and carefully measure the amount of water. After discussion, they complete the rest of the worksheet. Answers Page 108

1. Answers should indicate that as water is continuously recycled throughout the hydrologic cycle, the same water could have be used by a tyrannosaurus and now us. 2. Left to right: evaporation, transpiration, condensation, infiltration, precipitation 3. (a) water changes from liquid to gas (b) water changes from liquid to gas (c) water changes from gas to liquid (d) water can remain in liquid state as fog or rain, or change to a solid (if cold enough) in the form of snow, sleet or hail 4. Surface run-off is water flowing over the ground. Infiltration is water soaking into the ground. 5. (a) in the ocean as liquid (b) in the atmosphere as gas 6. Possible answer: The hydrologic cycle describes the movement of water on, above and below Earth’s surface.

Preparation • A large display chart of the water cycle would be useful when discussing the text on page 107. • Organise the equipment needed to make the solar stills on page 109. Each group’s still needs to be made from identical equipment and materials to be a fair test. The soil should have the same moisture content and consistency. The amount of soil and water needed will depend on the size of the tub. Soil should cover from 5 cm to 10 cm of the bottom of the tub (depending on size of tub). Water should be enough to make the soil quite damp. Each group needs to have the same amount of soil and water to put in their tub. Measuring cups used should have a scale marked in millilitres and be made from clear plastic/glass so water can be measured accurately.

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• Useful websites: Animations of how the water cycle works. − <http://www.youtube.com/watch?v=O_cOZzZfC8c> − <http://www.youtube.com/watch?v=x2jPsfy2iq8> − Interactive following the path of a water droplet in the water cycle. <http://oceanservice.noaa.gov/education/pd/oceans_weather_ climate/welcome.html/> (Then click on 'water cycle'.)

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• The water (or hydrologic) cycle can be likened to a series of reservoirs or storage areas, and the processes that cause water to move from one reservoir to another. The oceans are by far the largest reservoir as more than 70 percent of Earth is covered by ocean.

• Students predict which still will collect the most water and explain their prediction. The stills should not be disturbed in any way for several hours. Students can observe what is happening but should not touch or move them as this can cause the water to drip back into the soil and not collect in the cup.

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Teacher check

Students should correctly predict or later discover that the water collected in the cup is condensed water vapour which has evaporated from the soil. The still(s) placed in direct exposure to the sun will collect more water than those in shade or a position of less heat.

• It is assumed students understand the concept of the three main states of matter—solid, liquid and gas. • The solar still activity on page 109 is best completed on a warm, still day. Wind can interfere with the stability of the still and the plastic covering, and evaporation. The warmer the day, the more water will be evaporated and collected in the cup. Discuss what a solar still is (but don’t give too much away as to how it works). Explain that the class will be broken into groups, with all groups making identical solar stills. Ask them why this is necessary (fair test). AUSTRALIAN CURRICULUM SCIENCE

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What is the water cycle? – 1 Did you know the same water is here on Earth as was here in the age of the dinosaurs? In fact, the same water has been here since Earth itself was first formed. It’s all due to the water cycle. The water cycle is also known as the hydrologic cycle (‘hydro’ means ‘water’). It describes the movement of water above, on and below Earth’s surface. Water covers 70 per cent of our planet, with 97.5 per cent found in oceans. The remaining 2.5 per cent is found on and below land and in the atmosphere. Water is constantly being recycled around the ocean, atmosphere and land. In order to do this, water has to change state between liquid, solid and gas. There are several processes that make up the water cycle. These are explained below.

r o e t s Bo r e p ok u S SUN

CLOUDS clouds

PRECIPITION PRECIPITATION

surface run-off

EVAPORATION (water vapour)

TRANSPIRATION ocean river RIVER

lake RIVER

INFILTRATION

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Evaporation takes place and the water becomes a gas—water vapour. Water also evaporates from the leaves of plants through a process called transpiration. In large tropical rainforests, a vast amount of water will transpire through leaves. Rising air currents take the water vapour into the atmosphere. Here, cooler temperatures cause condensation to occur. In this process, the water changes from a gas back to a liquid. The vapour turns into tiny water droplets suspended in the air. These droplets combine with others to form clouds (or fog at ground level). When the temperature and atmospheric pressure are right, precipitation occurs and the droplets fall to Earth. Rain is the most common form of precipitation. Other forms are fog drip, hail, snow and sleet. In the last three forms, water has changed from a liquid to a solid in the form of ice (due to temperature). It will remain solid if it falls in an area where the temperature is at or below freezing point.

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Precipitation may fall into the ocean, other bodies of water or on land. Much of it flows over the ground as surface run-off, where it may end up in a lake, river, sea or ocean. Infiltration is the process in which precipitation soaks into the ground. Some water infiltrates deep into the ground until it reaches an aquifer, an underground layer of porous rock, which can store huge volumes of fresh water. Scientists have discovered some interesting facts about the life of water molecules in the water cycle. Over a 100-year time frame, a water molecule will spend 98 years in the ocean in liquid form, 20 months as solid ice, about two weeks in lakes or rivers in liquid form and about a week in the atmosphere as a gas.

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CONDENSATION

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Hydrologic cycle

What is the water cycle? – 2 Use the text on page 107 to complete the following. 1. Explain how the water you used in washing your teeth this morning could also have been used by a tyrannosaurus drinking swamp water.

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2. In the diagram of the water cycle, label the boxes with the correct processes.

3. Explain any changes of state water goes through during each of these processes in the water cycle. (a)

evaporation:

(b)

transpiration:

4. What is the difference between surface runoff and infiltration?

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(d)

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5. Where, and in which state does a water molecule spend: (a)

most of its ‘life’?

(b)

least of its ‘life’?

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6. Rewrite this sentence so it is correct: The hydrologic cycle describes the movement of water on Earth’s surface.

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Mini solar still experiment A solar still is a device for collecting water, using help from the sun. A simple solar still can be made with readily available materials. In a small group, follow the procedure for making the still and answer the questions about your observations. Equipment:

â&#x20AC;˘ 1 plastic tub â&#x20AC;˘ plastic cling wrap â&#x20AC;˘ wide tape

â&#x20AC;˘ 1 plastic cup â&#x20AC;˘ measuring jug â&#x20AC;˘ cups water

â&#x20AC;˘ 1 large marble â&#x20AC;˘ cups soil â&#x20AC;˘ measuring cup

What to do:

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í˘ą Add soil to bottom of tub. Spread evenly. í˘˛ Add water, sprinkling evenly over soil.

í˘ł Place cup in centre of tub. Partially submerge for stability.

í˘ľ Place marble on plastic directly over cup so it forms a depression.

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í˘´ Seal tub securely with plastic and tape.

í˘ˇ Observe over several hours. Do not disturb still. Predictions, results and conclusions: 1. Where do you think the water will come from?

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3. Complete the table with your results.

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Amount water (mL) collected

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ÂŠ R. I . C.Publ i cat i ons Predict which still will collect the most water and give a reason for your answer. â&#x20AC;˘f orr evi ew pur posesonl yâ&#x20AC;˘

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Which still(s) collected the most water?

(b)

Were your answers in Questions 1 and 2 correct? YES

(c)

If not, discuss the results and write a correct explanation.

5. On the back of this sheet, explain any problems you had with the experiment and note ways to solve them. R.I.C. PublicationsÂŽ

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í˘ś Place solar still in location decided with rest of class. Label with â&#x20AC;&#x2DC;Aâ&#x20AC;&#x2122;, â&#x20AC;&#x2DC;Bâ&#x20AC;&#x2122; etc. as decided.

What natural factors influence the water cycle? Content focus: Inquiry skills focus:

Answers

Investigating natural factors that influence the water cycle

Page 112

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

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• Prevailing winds can affect the amount of precipitation an area receives according to the amount of moisture they are carrying. For example, if coming from across the ocean they bring moisture onto the land and move drier air away. Preparation

• A large display chart of the water cycle would be useful when discussing the text on page 111.

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• The text provides a summary of the way in which several important natural factors affect the water cycle. A useful site giving information about the water cycle, including factors influencing it, is: <http://ga.water.usgs.gov/edu/watercycle.html>.

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• This unit is best completed after the previous unit (pages 106 to 109). Revise the meaning of terms used in the text, in particular ‘latitude’ (distance north and south of equator) and ‘altitude’ (distance above sea level). • The experiments on page 113 could be done in small groups and not necessarily at the same time or on the same day. Depending on the natural heat in the classroom, the sponges may take more than one day to dry. Ensure there are no extra fans or heat from a room heater as this will affect the evaporation rate.

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• Organise the equipment needed for the experiments on page 113. Sponges, plates, study lamps (the type that can be directed downwards) and fans need to be identical so the test is fair. The lessons

1. Answers will vary according to the type of weather and the season being experienced in the students’ location. 2. (a) increases as temperature increases (b) warmer temperatures cause stoma to open and transpiration to occur, opposite if temperature is too cool (c) temperatures must be cool enough for condensation to occur (d) temperature determines type of precipitation; e.g. freezing temperatures produce snow 3. (a) low humidity (b) low moisture content in soil (c) higher altitude (d) steep slope 4. Wind speeds up the rate by moving the air about and causing it to expand, resulting in more ‘room’ for water vapour in the atmosphere for evaporation and transpiration. 5. A clay soil does not absorb as much water as a sandy soil so less infiltration occurs. 6. A mountain range can cause moist air to rise, condense and eventually precipitate. Science as a Human Endeavour question Nature and development of science Students should discover that a desert is defined as an area with less than 254 mm rain/year. Antarctica receives about 50 mm in the interior and 200 mm along the coast. It is so cold that almost all precipitation is snow. There is little evaporation so the snow compresses into ice sheets that have built up over time. Note: Students could use the following websites to help complete the activity. <http://www.coolantarctica.com/schools/Easy/whats_it_like_in_ Antarctica-easy.htm> <http://en.wikipedia.org/wiki/Climate_of_Antarctica>

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• Discuss the factors students must consider and take into account to make each experiment a fair test. As a class, work out how much water will wet the sponge all the way through. [Use a spare sponge(s).] Each group must measure and use the same amount. They record this on the worksheet in the ‘You will need’ section.

Students should discover that Sponge A under the lamp’s heat and Sponge A under the fan’s breeze both dried faster than the sponges marked B. The higher temperature from the lamp made the water molecules in the sponge move faster. They gained enough energy to ‘escape’ into the air as a gas, or evaporate. Moving air (or wind) from the fan moved the surrounding air around the sponge making more room for water molecules in the sponge to evaporate. Wind also ‘pulled’ out water molecules from the top surface of the sponge as they were already weakly bound to others. Students should discuss any problems they had with the experiments and find ways to solve them. Students could try experimenting with different strength light bulbs and slower or quicker fan speeds to see how the evaporation rate compares.

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What natural factors influence the water cycle? – 1 The continuous movement of water below, on and above Earth’s surface is known as the water (or hydrologic) cycle. In places such as a tropical rainforest, the water cycle is easily observed as water is constantly present. However, in a desert area, the water cycle seems to be non-existent, until it eventually rains, which may only occur once every few years. Water needs to be present for the water cycle to work—to evaporate, condense, precipitate and so on. There are many natural factors that influence the way the processes in the water cycle work.

released) to open. Cooler temperatures cause the stoma to close, releasing less water that can be evaporated into the atmosphere. If the moisture in the soil is low, plants also transpire less in order to survive. Humidity and wind affect transpiration in the same way they affect evaporation. Different plants transpire at different rates; e.g. a cactus retains nearly all its water.

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Condensation occurs when water vapour in the atmosphere changes to a liquid state. Clouds form (or fog at ground level) which may produce precipitation, usually in the form of rain. Temperature and air pressure affect condensation. Temperatures have to be cool enough in the atmosphere for water vapour to condense. Air pressure is lower at higher altitudes, which results in lower temperatures.

Evaporation occurs when solar radiation from the sun heats up water to a point where it changes from liquid to gas. Evaporation is mainly from oceans, but can be from any large or small body of water. Evaporation increases as the temperature increases. The more direct solar radiation a place containing water receives, the greater the evaporation rate. Cloud cover can prevent direct solar radiation. The sun’s rays are less direct the higher the latitude; e.g. in the polar regions. Humidity (the amount of water vapour in the air) also affects evaporation. The lower the humidity, the drier the air is, which results in faster evaporation. Wind speed is another factor affecting the rate of evaporation. Wind moves air about, causing it to expand. This means more ‘room’ for water vapour in the atmosphere.

Precipitation is water released from clouds in the form of rain, snow, hail, sleet or fog drip. Temperature is the factor influencing the type of precipitation. Snow forms from water droplets in clouds where the temperature is below freezing. Hail forms in a similar way in thunderclouds. The areas in which precipitation falls is influenced by factors such as distance from mountain ranges or the ocean, and prevailing winds (those which blow most often).

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Infiltration is the process in which precipitation soaks into the ground. Much of this water is stored in aquifers for long periods of time until it eventually seeps into rivers, oceans etc. and again becomes active in the water cycle. Precipitation falling on steeply sloped land will run off more quickly into catchment areas or oceans and so on and not soak into the ground. Clay soils absorb less water and at a slower rate than sandy soils. Heavy vegetation slows the movement of runoff, giving it more time to soak in.

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Transpiration is evaporation of water through the leaves of plants. As air temperature increases, the warmer air around the plant causes its stoma (tiny holes where water is

Mountains force moist air to rise, which condenses in cooler temperatures until precipitation occurs. R.I.C. Publications®

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The main processes are evaporation, transpiration, condensation, precipitation and infiltration. Factors such as temperature, humidity, latitude, altitude and wind speed can affect each process.

What natural factors influence the water cycle? – 2 Use the text on page 111 to complete the following. 1. On the day you are completing this, is the water cycle easily observed in the location where you live? Explain why or why not.

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2. Describe how temperature affects each of these processes in the water cycle. evaporation

(b)

transpiration

(c)

condensation

(d)

precipitation

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(a)

3. Tick the factor needed to produce the rate of each process in the water cycle. (a)

low moisture content in soil

higher condensation rate: higher altitude

lower altitude

(d)

lower infiltration rate:

flat land

steep slope

4. How does wind affect evaporation and transpiration?

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(c)

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(b)

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5. What is the difference in which the way a clay soil and a sandy soil allow water to infiltrate?

6. What influence can a mountain range have on the water cycle?

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Evaporation rate experiments Evaporation is the process in which water changes from a liquid to a gas. Various factors can change how fast evaporation occurs. In a small group, follow the instructions to find out how temperature and wind can affect evaporation rate. You will need: â&#x20AC;˘ 2 identical kitchen sponges â&#x20AC;˘ measuring cup â&#x20AC;˘ â&#x20AC;˘ 2 identical plates, labelled A and B â&#x20AC;˘ electric fan (Exp. 1 only) â&#x20AC;˘ study lamp with 60 watt globe (Exp. 2 only) Experiment 1

mL water

What to do:

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í˘ą Place a kitchen sponge on each plate. A B í˘˛ Pour mL water over each. í˘ł At the same time, place Plate A directly under lamp and Plate B away from lamp, at room

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temperature and not in direct sunlight.

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í˘´ Observe the sponges at regular intervals, shortening the time between observations as the sponges get closer to being fully dry.

Predictions, results and conclusions:

ÂŠ R. I . C.Publ i cat i ons Sponge (under Sponge B (room temp.): â&#x20AC;˘Af orheat): r evi ew pur po ses on l yâ&#x20AC;˘

2. Record the time taken for each sponge to dry.

(b)

Were your answers to Question 1 correct? YES

If not, discuss the results and write a correct explanation on the back of this sheet.

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What to do:

í˘ą Repeat Steps 1 and 2 in Experiment 1. í˘˛ At the same time, place Plate A 30 cm from fan and Plate B away from fanâ&#x20AC;&#x2122;s draught. í˘ł Observe the sponges at regular intervals, shortening the time between observations as

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the sponges get closer to being fully dry. Predictions, results and conclusions:

1. Predict which sponge you think will dry the quicker and give a reason for your answer.

2. Record the time taken for each sponge to dry. Sponge A (under fan):

Sponge B (room temp.):

3. (a) Were your answers to Question 1 correct? (b)

YES

If not, discuss the results and write a correct explanation on the back of this sheet.

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1. Predict which sponge you think will dry quicker and give a reason for your answer.

What human factors impact on the water cycle? Content focus:

Inquiry skills focus:

Investigating how human management of water can impact on the water cycle

• The aim of the experiment is for students to identify how water is stored in aquifers and how this water can become contaminated by pollutants above the ground.

Identifying issues connected with the use and management of water

• Before each step in the experiment is performed, discuss what should happen.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

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Background information

Answers Page 116

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1. (a) 70 per cent (b) 97.5 per cent (c) 2.5 per cent (d) 1960s (e) 70 per cent 2. The rivers that feed the Aral Sea were diverted for irrigation. Precipitation was not enough to maintain its water level and 70 per cent has evaporated. It has changed how the water cycle works in the region. 3. Water does not disappear or become lost forever in the water cycle. The water once in the Aral Sea water cycle has shifted to other places in the water cycle. 4. Evaporation rates are high in large water bodies such as dams, which causes the water table to rise and prevents water from infiltrating the soil to replenish groundwater systems. Damming prevents run-off continuing downstream and replenishing aquifers. 5. If too much water is drawn from wells in aquifers, the water in that part of the water cycle will not be maintained. 6. Activities such as building roads affect water run-off in the water cycle as water cannot soak into paved and bituminised surfaces.

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• The Aral Sea has lost 70 per cent of its volume since work began in the 1960s to divert its two feeder rivers for irrigation. The loss of water has also reportedly changed the climate—hotter, drier summers and longer, colder winters.

• Depletion of water in aquifers and groundwater is not as obvious as in water bodies such as rivers and lakes. There is less visual evidence and the effects of human mismanagement take longer to be seen. Careful monitoring needs to be done by authorities worldwide.

• If students have constructed the model of the aquifer correctly, they should see how water and pollutants can eventually infiltrate throughout groundwater and aquifers, even under confining layers. The spray bottle should produce reddish tinged spray when depressed (pollutant).

Preparation

• Organise the equipment needed for the experiment on page 117. The sand and rocks used should be clean so sediment or dirt from them does not cloud the water before students see the effects of the ‘pollutants’ (cocoa and food colouring).

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• Useful websites: − <http://www.epa.gov/ogwdw000/kids/flash/flash_aquifer.html> (This flash website shows pictorial and written steps of making the aquifer on page 117. Note: It is an American website with imperial measurements.) − <http://www.youtube.com/watch?v=Z0Pi61SyVSM> (video explaining the Aral Sea disaster) − <http://www.nwc.gov.au/www/html/335-groundwater-andaquifers.asp?intSiteID=1> (information about groundwater and aquifers)

• Students could evaluate how well they constructed their aquifer and give solutions to any problems they encountered.

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• This unit is best completed after those on pages 106 to 113. Briefly revise the water cycle processes before discussing the text on page 115.

• Help students identify human activities in their local area that could have an impact on the water cycle; e.g. Does a bore supply irrigation for the school oval? Do they live in a large city/town with lots of roads and paved areas? • The aquifer experiment could be treated as a whole-class activity with different students carrying out different steps while the rest of the class observes. It could also be done in small groups. The website listed first above could be helpful in following the instructions.

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What human factors impact on the water cycle? – 1 hot, arid areas. This causes the water table to rise closer to the surface and prevents water from infiltrating the soil to refill aquifers or groundwater systems. Damming water also stops run-off continuing downstream and infiltrating aquifers and other catchment areas. Again, the water in the water cycle has shifted.

Water covers more than 70 per cent of the surface of our planet. Of this, 97.5 per cent is salt water from the oceans, with the remaining 2.5 per cent being fresh water. Most fresh water is part of the Antarctic ice sheet, with the rest being found in glaciers, rivers, lakes, wetlands, soil, aquifers (underground storage areas) and the atmosphere. Due to the water cycle, this fresh water is constantly circulated. However, there are several ways human management of fresh water impacts on the water cycle.

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injection wells

bedrock

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Human activities such as clearing land for farming, building roads and constructing towns and cities have changed the way run-off in the water cycle flows over and through the land. For example, water cannot soak through the paved and bituminised surfaces in a city. Drainage systems need to be constructed to direct the run-off from stormwater and wastewater back to replenish water bodies such as aquifers, rivers, wetlands and oceans.

The construction of dams and reservoirs has an impact on the water cycle. These are built for water supply, hydro-electric power, flood control, irrigation or a mixture of these purposes. Evaporation rates are high in these large bodies of water, particularly in R.I.C. Publications®

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Carefully observe the area in which you live. Can you identify any ways people may have had an impact on the water cycle?

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A dramatic example is what happened to the Aral Sea, located in Central Asia. This sea was once the fourth largest in the world. In the 1960s, the two rivers that flowed into the sea were diverted by a series of dams and canals to create an irrigation system in the surrounding desert areas for agricultural purposes. Precipitation was not enough to maintain the Aral Sea’s water supply. Over the years, about 70 per cent of its volume of water has gradually evaporated. Ships and boats that once docked at fishing ports along the sea were abandoned as the water dried up. This example shows how humans can negatively affect the water cycle of a region. It should be noted that the same amount of aquifer water is still present in the water cycle—it has ‘shifted’ to another area.

Government authorities and private users inject bores into groundwater supplies and aquifers to irrigate household and public gardens, sports arenas, golf courses, commercial fruit and vegetable crops, dairy and beef pastures; and, in some cases, provide mains/scheme water needs. Water authorities must monitor the amount taken so these underground water supplies are maintained and humans do not have a negative impact on the water cycle.

What human factors impact on the water cycle? – 2 Use the text on page 115 to complete the following. 1. Use numbers, percentages and dates to answer the following. (a)

Percentage of water covering Earth

(b)

Percentage of salt water on Earth

(c)

Percentage of fresh water on Earth

(d)

Decade in which the Aral Sea began drying up

(e)

Approximate volume of water the Aral Sea has lost

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2. Summarise human impact on the water cycle in the Aral Sea region.

3. Explain why this statement is incorrect. ‘The water that was once in the water cycle of the Aral Sea has been lost forever.’

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4. Describe two ways dams and reservoirs can have an impact on the water cycle.

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5. How can drilling wells into aquifers affect the water cycle?

6. Explain how human activities can impact on run-off in the water cycle.

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Aquifer experiment Wells can be drilled into underground water sources called aquifers. The water can be used for purposes such as irrigation or drinking water. Water in aquifers can become contaminated from pollutants. Follow the procedure for making your own aquifer, carefully observe what happens and write a summary about what you learnt. You will need:

â&#x20AC;˘ clear plastic container, approx. 15 x 20 x 20 cm

â&#x20AC;˘ tape

â&#x20AC;˘ approx. 400â&#x20AC;&#x201C;500 g modelling clay

â&#x20AC;˘ 1 drinking straw

â&#x20AC;˘ approx. 5 cups sand (enough to cover 2â&#x20AC;&#x201C;3 cm along bottom)

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â&#x20AC;˘ approx. 6 cups small aquarium-type rocks

â&#x20AC;˘ 1 eyedropper

â&#x20AC;˘ 1 cup cocoa or drinking chocolate

â&#x20AC;˘ 1 spray bottle

â&#x20AC;˘ 1 small piece green felt

â&#x20AC;˘ red food colouring

â&#x20AC;˘ bucket clean water

â&#x20AC;˘ measuring cup

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Procedure:

í˘ą Tape straw to one side of container, 1â&#x20AC;&#x201C;2 cm from bottom. (This represents the well.) í˘˛ Pour sand over entire bottom of container.

í˘ł Use cup to gradually pour water over sand until wet but no â&#x20AC;&#x2DC;puddlesâ&#x20AC;&#x2122; on surface. Observe how the water remains around the sand particles as it does in an aquifer.

ÂŠ R. I . C.Publ i cat i ons f o rr e vi e w pur posesonl yâ&#x20AC;˘ Pour aâ&#x20AC;˘ small amount of water onto of container on top of sand. (This represents a confining layer in an aquifer that prevents water from infiltrating.) clay. Observe how the water stays on top and only flows into sand not covered by clay.

surface water (lake)

confining layer

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í˘ś Add rocks over all of sand and clay to form another layer on top of an aquifer. Slope the rocks on one side to form a â&#x20AC;&#x2DC;hillâ&#x20AC;&#x2122; and a â&#x20AC;&#x2DC;valleyâ&#x20AC;&#x2122;.

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groundwater in aquifer

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í˘ˇ Pour water over aquifer until about 2 cm from top of hill. Observe how a small â&#x20AC;&#x2DC;lakeâ&#x20AC;&#x2122; has formed. This is â&#x20AC;&#x2DC;surfaceâ&#x20AC;&#x2122; water and water below clay is â&#x20AC;&#x2DC;groundâ&#x20AC;&#x2122; water.

í˘¸ Place felt over hill and attach with a bit of clay. (This represents grass.) í˘š Sprinkle cocoa onto grass. (This represents pollutants like fertilisers.) 10

Spray water over cocoa. Observe how this â&#x20AC;&#x2DC;pollutionâ&#x20AC;&#x2122; soaks through the grass and into the surface water.

Inject food colouring into aquifer about 3 cm from straw. (This represents pollutants like chemicals that get emptied into surface water.) Observe how this â&#x20AC;&#x2DC;pollutionâ&#x20AC;&#x2122; gradually infiltrates the aquifer under the confined layer.

Remove top of spray bottle and insert stem into straw. Depress trigger to pull up water from well. Explain what you think will happen and write a summary about what you have learnt on a separate sheet of paper.

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í˘´ Mould and press clay to form a flat section over half the bottom

What are some advances in the treatment and management of water? Science as a Human Endeavour units:

Nature and development of science Use and influence of science Identifying advances made with how water is treated for household and industrial use Identifying that water use, treatment and management involves applying technology from different areas of science Understanding the importance of Aboriginal and Torres Strait Islander contributions to water management Investigating issues involved with recycling greywater and blackwater

Inquiry skills focus:

Preparation • Students will need access to the internet and nonfiction resources to compile their report on page 121.

r o e t s Bo r e p ok u S The lessons

• After treating the text on page 119, discuss with the students where their school and/or household water supply originates; e.g. reservoir, desalination plant etc. Note: An excursion to a water treatment plant or reservoir would benefit the students’ understanding of this unit. • Students could work individually, in pairs or as a small group to complete the report on page 121. The suggested websites given in the first column provide relevant information, as will other websites and resource material they find. Students should plan how to present their report; e.g. charts, diagrams and written/typed information to display; PowerPoint™ display and so on.

Questioning and predicting Planning and conducting Processing and analysing data and information Communicating

Answers Page 120

Background information

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Content focus:

− <http://www.savewater.com.au/how-to-save-water/in-the-home/ grey-water> − <www.watercorporation.com.au/_files/PublicationsRegister/11/ Greywater_Reuse_and_Recycling.pdf>

1. A substance that makes something dirty or polluted. 2. Answers should include the following points: only treated water to improve taste, were unaware water could be contaminated with deadly bacteria, placed hot metal instruments in water to treat it, manually filtered it through cloth or sand. 3. microscope 4. physiology/microbiology/biology/chemistry, sanitary engineering/ public health education 5. (a) filtration (b) storage (c) coagulation (d) disinfection (e) sedimentation 6. Possible answers: (a) In what areas are Aboriginal Australians and Torres Strait Islanders helping make decisions about water use and management? (b) Who was the English physician who identified how cholera got into a water supply? (c) What will indigenous water resource knowledge assist in?

• The world’s first metropolitan treatment plant was built in Paisley, Scotland, in 1804. The plant depended on sand filters.

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• Useful websites: − <http://water.epa.gov/learn/kids/drinkingwater/ watertreatmentplant_index.cfm> (text links to a diagram of processes in the water treatment cycle) − <http://www.qsa.qld.edu.au/downloads/early_middle/el_ support_indig_resources.pdf> (Teaching ideas and website links relating to indigenous perspectives regarding sustainability of water. Refer to pages 5 and 6 of the document.)

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• Greywater is water from plumbing systems such as washing machines, showers and baths. When treated properly, it can be reused for purposes such as watering the garden. Blackwater is water from toilets, urinals, bidets and water used to wash nappies. It can be treated for use as part of a fertiliser program.

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• There are other issues concerning water use and management that have not been discussed in this unit. Students could research to find out about them; e.g. desalination plants, bioremediation, or water pollution issues in their local area.

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Teacher check

• The following websites could be useful for students in completing the report about greywater and blackwater on page 121: − <http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/ pages/Grey_water_-_recycling_water_at_home> − <http://en.wikipedia.org/wiki/Blackwater_(waste)>

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What are some advances in the treatment and management of water? – 1 The water we use every day is obtained from sources such as reservoirs, rivers, lakes and aquifers. Before use, it is treated to remove contaminants to make it safe for drinking, washing and other uses in homes and industries. In the past, people tried simple treatment methods for the sole purpose of improving the taste of water. These methods included boiling it, placing hot metal instruments in it and manually filtering it through cloth or sand before drinking it. The aim was to try to get rid of the impurities that often gave it an unpleasant taste. People then did not realise that even if water tasted clean, organisms such as those that cause cholera (an often fatal disease of the digestive tract) could still be present.

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Our understanding of why and how water should be treated has evolved through a wide range of sciences and technologies. For example, in the mid-19th century, an English physician, John Snow, identified that sewage from a cesspool leaking into a water supply was the cause of cholera in a specific street. The invention and development of the microscope led to microbiologists (such as Robert Koch and Fillipo Pacini) isolating and identifying deadly organisms, such as the cholera bacterium, that can live in water. Scientific researchers in areas such as biology and chemistry, and sanitary engineers, educators in public health and other industries connected with science and technology, have all contributed to the ways in which our water is treated and managed today.

1. Coagulation: Chemicals are added to the water to form sticky particles. Tiny particles of dirt etc. suspended in the water stick and coagulate to make heavier particles.

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3. Filtration: The water passes though filtration, consisting of small grains such as charcoal, sand or coal, to remove any tiny particles still in suspension.

STORAGE

SEDIMENTATION

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2. Sedimentation: The flow of water is slowed so the particles from Step 1 sink to the bottom. The clear water then proceeds to the next step.

COAGULATION

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4. Disinfection: Chemicals such as chlorine are used to kill bacteria and other microorganisms.

5. Storage: Water is stored in a reservoir of some form. From there, it flows through pipes to households and industries.

DISINFECTION

In Australia, the knowledge of traditional Aboriginal Australians and Torres Strait Islanders is being used to help make decisions about water use and management in areas such as Kakadu National Park and the Murray-Darling Basin. Indigenous methods of sustainability, including use of water, have developed over thousands of years. This resource of knowledge helps greatly with understanding the interaction of water bodies such as rivers, wetlands, coastal offshore ocean, groundwater and surface water. R.I.C. Publications®

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The following diagram shows the basic steps of the water treatment process in a treatment plant.

What are some advances in the treatment and management of water? – 2 Use the text on page 119 to complete the following. 1. Explain the meaning of the word ‘contaminant’.

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2. In your own words, write a paragraph to describe the major differences between the methods or reasons water was treated in the past compared with today.

3. What invention assisted scientists to identify cholera?

4. List five sciences or industries mentioned in the text that have contributed to the advances in water management and treatment.

water passes through small grains

(b)

step before water flows to households

(c)

chemicals form sticky particles in water

(d)

microorganisms are killed

(e)

particles of dirt etc. sink to the bottom

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(a)

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5. Name the steps in the water treatment process each of these describes.

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6. Write a question for each of these answers. (a)

Kakadu National Park and the Murray-Darling Basin.

(b)

John Snow

(c)

It will assist in understanding the interaction of bodies of water.

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Greywater and blackwater investigation Have you heard the terms ‘greywater’ and ‘blackwater’ being used? Both need to be carefully considered in relation to water recycling. 1. Research to prepare a report that compares both terms. Make notes next to each of the headings in the table to assist you in planning your report. 2. Work out what websites, nonfiction material and other resources you will need. 3. Plan how you will present your report.

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Are there any concerns with recycling it?

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What are any benefits in recycling it?

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Can it be safely recycled? If so, how?

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Definition

Blackwater

What are Newton’s laws of motion? Content focus: Inquiry skills focus:

• The importance of friction as a force acting on moving objects should be discussed with students. They need to understand that it is another invisible force that hinders movement and causes objects in motion to come to rest. Friction can result when two surfaces come into contact with each other and when an object is moving through air or water. There are both positive (e.g. tyres gripping the road) and negative (e.g. wear and tear on moving engine parts) effects of friction.

Applying forces to objects - Newton’s laws Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• Before commencing the experiment, explain what the students will be doing and ask them to predict what will happen when their fingers are taken away.

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• Newton’s laws are concerned with ideal motion and have enabled scientists to describe many different types of motion. However it should be noted they do not take into account air resistance and other forms of friction. It is these invisible forces that cause moving objects to eventually stop. In space this doesn’t happen. • The pen or eraser and paper activity described in the text on page 123 can be used to demonstrate the effect of friction by repeating the experiment using other materials with a rougher surface and greater friction.

Page 124

1. (a) Forces are pushes and pulls. (b) We can see the effect they are having on the object. (c) They are represented by the length and direction of an arrow. 2. (a) 3rd (b) 2nd (c) 1st 3. (a) 3rd (b) 2nd (c) 2nd (d) 1st (e) 1st 4. (a) The ball the bigger boy is about to kick should be circled (b) The smaller rock should be circled 5. Newton’s third law. The force pushing down on the trampoline causes a reaction in the opposite direction Science as a Human Endeavour question Use and influence of science This relates to Newton’s first law of motion. Students should be able to find some information about when seatbelt laws were introduced and made compulsory in their state or country. They may also be interested in the laws pertaining to restraining devices for younger children. Statistics concerning trauma reduction and seatbelts are also readily available on the internet.

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• A force can be a push, a pull or a twist and is exerted in a specific direction. Forces can be measured and are expressed in newtons. Forces can cause a object to change direction if it’s moving or they can change an object’s speed or shape.

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• They will need to work cooperatively in groups of two or three to block the holes and ensure the water stays in the carton until it has been filled and suspended.

Physical sciences

1. It was suspended to allow the carton to spin. 2. The effect of the force on the water pushing down as it left the carton could be observed first. 3. When the water flows out of the holes, it pushes the carton in the opposite direction. Since the holes are at the bottom corner of each face of the carton, this reaction causes the carton to spin in one direction. 4. The force was no longer being exerted. Conclusion: The action of the water caused an equal and opposite reaction. • When the experiment has been finished, evaluate the success or failure of the activity. Decide which steps worked and those that didn't and why. Develop improvements and repeat the experiment if necessary.

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• Students conducting the experiment on page 125 may be splashed with water. Protective clothing and perhaps bare feet are recommended.

The lessons

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• Useful websites: − <http://teachertech.rice.edu/Participants/louviere/Newton/law1. html> (a very simple animated demonstration of Newton’s laws of motion) − <http://www.neok12.com/Laws-of-Motion.htm>(more complex and comprehensive video explanations and demonstrations) − <http://swift.sonoma.edu/education/newton/newton_1/html/ newton1.html> (information and experiments for teaching Newton’s three laws of motion)

• Discuss all of Newton’s laws and provide further examples of each. Encourage students to think about or research to find others. • It will probably be necessary to explain that the forces of friction and gravity also affect how objects move, why they stop and that Newton’s laws are more easily observed in space where there is no gravity. Information about these concepts is provided on pages 127 and 135. • Compile a wall chart of pictures, photos, illustrations and written descriptions to demonstrate each of the three laws. Students could plan, set up and take their own photographs to add to this chart.

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What are Newton’s laws of motion? – 1 Sir Isaac Newton (1642–1727) established laws of motion to explain how and why things move. It is amazing that after such a time, many people still considered his laws to be the most important ones in physical science. These laws can explain and help us to understand many of the things we do, see and read about; such as how the moon orbits the Earth, how things travel across a surface and how a rocket is launched into space. Newton’s laws explain the relationship between force and motion. Forces, which we can think of as pushes or pulls, can cause motion. A force has size and direction. We can’t see force but sometimes we know it’s there because we can see its effect. On diagrams, a force is represented by an arrow showing the direction of the force, so we can tell if it’s a push or a pull. The length of the arrow shows the size or strength of the force. Force is measured in newtons.

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Newton’s first law: An object continues at rest or in motion in a straight line with a constant speed unless acted on by an external force.

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This law is sometimes called the law of inertia.

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It means that a body at rest remains at rest unless a force is applied to it. This law explains why it’s possible to pull a sheet of paper out from under an object without moving the object. Try it with a pen or an eraser. You will need to practise removing the paper quickly so there isn’t any force applied to the object. This first law also means that a body in motion remains in motion unless a force is applied to it. This explains what happens if you’re on a skateboard going at a constant speed and your board hits a curb and stops suddenly. You would continue moving in a straight line in the same direction at the same speed until you collided with something like a tree or the ground.

Newton’s second law: Acceleration or change in motion is produced when a force acts on a mass. The greater the mass of the object, the greater the amount of force needed to accelerate it. This second law is sometimes called the law of acceleration.

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It describes how mass, force and acceleration are related using the equation: F = ma.

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It explains that it takes more force to move or accelerate an object that has more mass. So you would need more force to move an elephant than a mouse, because of its greater mass. You could also tell how hard a moving ball is going to hit if you know its mass and how fast it is speeding up. (This is its acceleration.) So if someone throws the ball to a catcher, how hard the ball hits the catcher’s hands depends on two things—the mass of the ball and whether it is speeding up or slowing down when it gets to the catcher. According to this law, you could make something hit with more force either by making it bigger or by throwing it faster.

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Newton’s third law: For every action there is an equal and opposite reaction.

It explains the upwards movement of a rocket. The gases from the rocket engine pushing down cause a reaction from the ground which pushes the rocket up. This reaction is visible, but many equal and opposite reactions can’t be seen. When you sit on a chair, the chair exerts an invisible upward force to balance the force of your body pushing down. If this didn’t happen, the chair would collapse.

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This third law is sometimes called the law of action and reaction.

What are Newton’s laws of motion? – 2 Use the text on page 123 to complete the following. 1. (a)

What are forces?

(b)

How do we know some forces are acting on an object?

(c)

How are the size and direction of a force represented?

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2. Which of Newton’s three laws of motion explains:

(b)

that heavier objects need more force to move than lighter ones?

(c)

the reason for wearing a bike helmet?

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how rockets get up into space?

3. Which law explains:

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(a)

when firefighters turn on their fire hose they are pushed backwards?

(b)

that cars are being made out of lighter materials to save money on fuel?

(c)

why Blane can throw a tennis ball further than a cricket ball?

(d)

why Tran crashed his bike and went flying over the handlebars?

(e)

4. Circle the object that will move faster.

(b)

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(a)

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5. Use one of Newton’s laws to explain what happens when you jump on a trampoline.

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Water wheel experiment You will be using a milk carton to make a water wheel to demonstrate Newton’s third law of motion that states ‘for every action there is an equal and opposite reaction’. You will need: • milk carton

• string

• jug of water

• pencil

• scissors

What to do: • Poke a hole in the bottom left corner of each side of carton. • Make a hole in the top flap of carton.

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• Push string through hole in top flap but leave carton open. • Take carton and water jug outside.

• Pour water into carton. • Tie string and hold or hang carton on a tree branch so it is suspended. • Take fingers off the holes and observe what happens. Observation

Describe what happened and draw a diagram.

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• Cover the four bottom holes with fingers. (You will need help to do this.)

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Analysis

1. Why did you need to hang the carton from string?

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2. What force effect did you observe first?

4. Why did it stop spinning when there wasn’t any water left in the carton? Conclusion How did this experiment demonstrate Newton’s third law?

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3. What did the equal and opposite force cause to happen?

How do balanced and unbalanced forces work? Content focus: Inquiry skills focus:

The lessons

Balanced and unbalanced forces, and friction

• Students should work in small groups to plan this investigation. Some students may find it difficult to work out that they can use marbles placed in the zip lock bag, tied with string and attached to the hook to move the block. It may be necessary to suggest they think about suspending the bag from the end of a table using the force of gravity to assist in moving the block as more marbles are added.

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

• In order to have a fair test, all but one of the variables in an investigation need to be controlled. In this case, the force acting on the block is the uncontrolled variable. Because the marbles placed in the zip lock bag are counted to measure this force, they must all be the same size to ensure a fair test.

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Answers

Page 128

1. (a) unbalanced (c) pushes 2. (a) false (d) false 3. (a) (i) unequal (iii) opposite (b)

• Friction is present when motion is attempted, even if the object doesn't move. There are two types of friction; static, which acts before the object moves; and dynamic, which acts after the object begins to move. • Friction produces heat. This fact has been recognised since earliest times. By using the heat released when sticks of wood were rubbed together, humans were able to produce fire. In more recent times, heat shields made from specially produced ceramic tiles have been necessary to protect spacecraft from the intense heat generated by friction as they return through the Earth's atmosphere. It is the heat generated by friction that causes wear and tear on the moving parts of machines.

(b) (d) (b) (e)

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• The result of a net force greater than zero is motion in the direction of that force. The concept of friction is relevant to unbalanced forces because it opposes motion. It is sliding friction, and air and water resistance opposing their motion that cause objects to eventually stop.

in the same direction 850 N false (c) true false (f) true (ii) unbalanced (iv) newtons

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• There are both advantages and disadvantages to friction. Without it, running and driving would be extremely dangerous. Devices such as tyre and shoe treads have been developed to increase friction. Smooth metals and other materials have been used to reduce friction on moving parts. • Useful websites: − <http://www.nsf.gov/news/special_reports/olympics/curling. jsp> (an explanation and video about the role friction plays in the Olympic sport of curling) − <http://www.scribd.com/doc/525784/Balanced-and-UnblancedForces> (a simple explanation of balanced and unbalanced forces)

250 N

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• Organise the equipment needed for the investigation on page 129. A small cup or bucket can be substituted for the zip lock bag if it can be attached by string and filled with marbles without tipping over.

250 N

Science as a Human Endeavour question Use and influence of science Students should be able to access information on the internet about this ancient Scottish sport in which science plays an important role. A suitable website with a video of the sport being played is listed in the useful websites section. Page 129 Students should find they need more marbles to move the rubber or sandpaper surface of the block. To find how many more times friction there was, they will need to divide the higher number of marbles needed by the smaller number.

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How do balanced and unbalanced forces work? – 1 • Forces can be pushes or pulls in a particular direction and are measured in newtons. • Forces can cause an object to stop moving, start moving or change how it’s moving. • Forces can not be seen but their effects can. • More than one force can act on an object at the same time. What happens to the object depends on the strength and direction of the forces. • Forces can work together or they can be opposites.

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• Forces can be balanced or unbalanced.

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Balanced forces are equal in size and act in opposite directions. Balanced forces do not cause a change in motion because they cancel each other out. The resulting or net force is zero.

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• Unbalanced forces can act in opposite directions. To find out the combined or net force of two forces acting in opposite directions, we need to find the difference between them. We do this by subtracting one from the other. The net force will be in the direction of the stronger force.

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Friction

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Any moving object produces another force that slows it down and eventually causes it to stop. This invisible force in exactly the opposite direction is called friction. Air and water resistance are examples of friction. A moving object needs to use extra energy to overcome friction. This can be an expensive disadvantage of friction but there are many advantages too. It is the friction between your bicycle wheel and its brake pad that allows you to stop, and it’s friction between the ground and your feet that makes it possible for you to run. Materials with a rougher surface produce more sliding friction than those with a smoother surface. This explains why car tyres have tread on them and why driving on icy roads can be so difficult and dangerous. R.I.C. Publications®

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• Unbalanced forces can both act in the same direction. To find out the combined or net force of two forces acting in the same direction, we add them together.

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Unbalanced forces are different from balanced forces because they cause a change in motion. They are not equal and opposite so they don’t cancel each other out and can be in the same or opposite directions.

How do balanced and unbalanced forces work? – 2 Use the text on page 127 to complete the following. 1. (a)

600 N

Are the two forces on car balanced or unbalanced?

(b)

Are they opposites or in the same direction?

(c)

Are they pushes or pulls?

(d)

What is the net force being applied to the car?

250 N

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2. Are these statements true or false?

(b)

Balanced forces are equal and act in the same direction.

(c)

The net force is the combined forces acting on an object.

(d)

To calculate the net force, you must add all the forces.

(e)

Forces are easily seen.

(f)

Forces are measured in newtons.

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Forces always cause motion.

Circle the correct words. The forces on the sled which a man is pulling with a force of 500 N and two dogs are pulling with a combined force of 250 N in the opposite direction are:

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(ii)

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3. (a)

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(a)

balanced/unbalanced

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(iii) in the opposite/same direction

(iv) measured in newtons or kilograms

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(b)

Add arrows to show the direction of the forces being applied to the sled by the man and the dogs. Then add the size of these two forces.

(c)

The sled will move to the left/right.

(d)

The net force is

4. Draw a diagram to show two boys applying forces of 300 N and 250 N in the same direction to pull a go-kart along a track.

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Friction on different surfaces In this investigation of friction, the force that opposes motion, you will be using marbles to measure the size of the force needed to overcome the friction on two different surfaces of a wooden block. Using this information, you can then work out how many times greater the frictional force is on one surface than on the other. Equipment: • block of wood with a cuphook screwed into one end and one surface covered with a material such as rubber sheeting or fine sandpaper which can be glued on

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• plastic zip lock bag Prediction

• marbles

• string

• scissors

(Before you make your prediction, hold the hook and slide the block across the table trying the covered surface then the opposite one to feel how it moves.)

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Procedure

Draw a diagram to show how you will carry out your investigation and list the steps.

Reliability (What will you need to consider to ensure it is a fair test?)

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Observations and measurements (How will you record your observations?)

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Communication (How will you present your results?)

Reflection (How would you change the method you used?)

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Analysis (What do your results show and were your predictions correct?)

What are simple machines? Content focus:

Simple machines, including levers

Inquiry skills focus:

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

Preparation • Bring in some examples of simple machines such as pliers, crowbars and bottle openers and discuss what each allows us to do more easily. Encourage students to suggest other similar simple machines and how they are used. The lessons • The investigation on page 133 requires students to measure the effort needed to move a load while changing the length of the effort arm.

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• Simple machines can be categorised as:

Answers

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− Inclined planes in which the force needed to raise an object a certain distance is decreased by increasing the distance. Often two inclined planes are put together to form a wedge. Examples include tacks and nails.

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• Machines deliver movement to a particular location from an input force applied somewhere else. Complex machines consist of moving parts such as levers, gears, cams, cranks, springs, belts and wheels but they are all based on simple machines.

• Variables need to be controlled in order to ensure a fair test and, in this investigation, there are two linked variables; i.e. the effort arm length and the effort. The investigation focuses on the relationship between these two variables.

1. (a) A machine is a device that makes it easier to do work such as lifting or moving heavy objects from one position to another. (b) levers, pulleys, wedges, screws, wheel and axles and inclined planes (c) an inclined plane (d) A ramp could be used to roll or pull an object up from one level to another. 2. Diagrams, class and examples of levers will vary. 3. (a) Using a machine with a high mechanical advantage can multiply the effort so it could lift heavier loads. (b) MA = load ÷ effort 4. (a) 5 (b) 2 (c) 3 (d) 1

− Levers are often used to change the direction of movement and to decrease the effort needed for it by applying it over a greater distance. Examples include claw hammers and bottle openers.

− Wheel and axles are like circular levers in which a gain in force is also traded with the distance travelled. The movement of the wheel is converted to shorter more powerful axle movements. Examples include steering wheels and screwdriver handles. − Pulleys use ropes or chains to transfer force. They can change a force’s direction or provide a force-for-distance trade off.

• Useful websites: − <http://www.design-your-homeschool.com/easy-scienceexperiments-machines.html> (information about a number of experiments with a variety of simple machines) − <http://www.enchantedlearning.com/physics/machines/Levers. shtml> (animated demonstration of class 1, 2 and 3 levers) − <http://www.dynamicscience.com.au/tester/solutions/ hydraulicus/simplemachineslevers4.htm> (simple mechanical advantage calculations using animations) − <http://www.dynamicscience.com.au/tester/solutions/ hydraulicus/simplemachineslevers6.htm> (demonstration of three classes of levers and their mechanical advantage)

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Page 133 1. (a) Yes (b) The longer the effort arm, the fewer the coins needed to move the load. 2. Teacher check 3. Teacher check 4. Teacher check. Using smaller units of measurement—i.e. smaller coins—would give a more accurate measure of effort. 5. Double the load would increase the effort needed to move it. Students can share their reflections about this investigation in small groups.

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− Screws can be considered inclined planes wrapped around a cylinder. While inclined planes use a linear force in a horizontal plane to lift vertically, screws lift vertically using a rotary force in a horizontal plane.

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What are simple machines? – 1 In the third century BCE, Archimedes identified five different types of simple machines resourceful humans used for doing work. They were levers, pulleys, wedges, screws and the wheel and axle. Later, Renaissance scientists added inclined planes to the list. By the sixteenth century, Galileo had produced a theory to explain the science of how unbalanced forces produce motion when these six simple machines are used. The word ‘machine’ can be linked to both the Greek word machos meaning ‘expedient’ or ‘making work easier’ and the Roman word machina meaning ‘a trick or a ‘device’. These links help us to define and understand more about machines.

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We use simple machines when we do everyday things like walk up a ramp, screw in a light bulb and cut paper.

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The purpose of a machine may be to reduce effort and to make it possible and easier to do such things as to lift or move heavy loads. With simple machines we can change the size and direction of a force to achieve a goal. We can do this by applying a force over a greater distance or for a longer time. Some levers use a greater force to move a load a greater distance. The lever is a commonly used simple machine. It consists of a rigid bar supported at a point which it rotates around. This pivoting point is called the fulcrum. A force, called the effort is applied to the lever at one point in order to move an object, called the load. There are three different classes of levers which depend on the positions of the load, the effort and the fulcrum First class levers have the fulcrum between the effort and the load. Examples include seesaws and scissors. effort Note: Some simple machines like scissors have two levers which rotate around one fulcrum.

effort

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Second class levers have the load between the fulcrum and the effort. Examples include wheelbarrows and nail clippers. Third class levers have the effort between the fulcrum and the load. They can need a greater force to move an object over a greater distance. Examples include fishing rods and tweezers.

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fulcrum

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effort load

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load

fulcrum

The mechanical advantage is the advantage a machine gives you to do work. Simple machines haven’t an energy source to add to the effort, but they can have a high mechanical advantage. This means they can multiply the affect of the effort to move a heavier load further. Some class 3 levers have a mechanical advantage of less than 1 and use more effort over a short distance to move a load over a greater distance. A lever’s mechanical advantage can be increased or decreased by moving the fulcrum. Mechanical advantage is calculated by dividing the load by the effort. MA = load ÷ effort 10 kg

5 kg

MA = 12 ÷ 3 = 4

MA = 10 ÷ 5 = 2 R.I.C. Publications®

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3 kg

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•

load

What are simple machines? – 2 Use the text on page 131 to complete the following.

(b)

Explain the meaning of the word machine.

Name six different types of simple machines.

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What type of simple machine is a ramp?

(d)

How do you think a ramp could be used as a simple machine?

2. (a)

(b) (c) 3. (a)

Draw a diagram of a lever and label the fulcrum, the load and the effort.

© R. I . C.Publ i cat i ons What class of lever did you draw? •f orr evi ew pur posesonl y• Give two examples of this class of lever. What is the benefit of using a machine with a high mechanical advantage?

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(b)

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(c)

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What is the formula for calculating mechanical advantage?

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4. Calculate the mechanical advantage of each lever. (a) Effort 20 N

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1. (a)

(b)

100 N

20 N

Effort 10 N

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MA =

MA = (c)

(d) 9N

Effort 8N

8N Effort 3N

MA = AUSTRALIAN CURRICULUM SCIENCE

MA = 132

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Lifting with levers You are going make a tabletop lever and investigate how changing the length of the effort arm affects how much effort is needed to lift a load. Prediction: Materials and equipment: â&#x20AC;˘ 30 cm wooden or metal ruler

â&#x20AC;˘ small flat stone/ 2 one dollar coins

â&#x20AC;˘ collection of 10 cent coins

â&#x20AC;˘ masking tape

Procedure:

â&#x20AC;˘

zip lock plastic bag

í˘´ r o e t s B r e oo í˘ľ p u k S í˘ś

í˘ą Use ruler to make a lever and tape stone/

Place lever on fulcrum so effort arm is 16 cm long and extending from table.

coins to one end of it. This is the load.

í˘˛ Hang plastic bag on the other end of the

Add coins to work out how many are needed to lift the load. Record results.

lever leaving it open so you can add coins to it. This is the effort.

Repeat with effort arm of 14, 12, 10 and 8 centimetres and record your results.

í˘ł Tape pen along the edge of desk to make fulcrum.

Results

Effort arm length

Coins needed

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â&#x20AC;˘ pen

ÂŠ R. I . C.Publ i cat i ons â&#x20AC;˘f orr evi ew pur posesonl yâ&#x20AC;˘ Analysis:

Does the length of the effort arm affect how much effort is needed to lift a load? No

Yes

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Explain the relationship between the load and the length of the effort arm.

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2. Were your predictions correct?

Yes

3. Was this a fair test?

Yes

Why?/Why not?

Reflection: 4. How could you change the method or equipment used?

5. What do you think would happen if you doubled the load?

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(b)

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1. (a)

What does gravity do to things on Earth? Content focus:

Inquiry skills focus:

• The video at <http://www.youtube.com/watch?v=5C5_dOEyAfk> shows a hammer and a feather being dropped at the same time on the moon and landing at the same time. Show the students this, then test what happens when objects are pulled down a ramp by gravity on Earth.

Gravity pulls all things towards the centre of the earth/Gravity affects the way things move/Gravity affects living things and gives objects with mass weight

Answers

Questioning and predicting Planning and conducting Processing and analysing data and information Evaluating Communicating

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• Gravity is a force of attraction that exists between any two objects with mass (the amount of matter an object contains), everywhere in the universe. The Earth has a large mass and its gravitational pull extends out into space in all directions. The further from the centre of Earth, the weaker the force becomes. • Weight is a measure of the force of gravity pulling on an object. With an increase in altitude (further from the centre of the Earth) from sea level to the top of Mount Everest (8850 metres), a person’s mass would be the same as at sea level, but his/her weight is different; there is a weight decrease of about 0.28%.

1. (a) mass: the amount of matter that an object contains (b) weight: the amount of force of gravity on an object with mass (c) gravity: a force attracting objects toward the centre of the Earth or towards any other object with mass (d) Newton: English scientist who wrote the universal law of gravitation (e) tides: rise and fall of the sea due to the attraction of the moon (and sun) 2. The moon’s gravity attracts bodies of water on earth, which move, creating ocean tides. 3. Plant roots usually grow towards the pull of gravity, and shoots and stems grow against it. 4. On the top of Mount Everest (the highest mountain), your weight would be less. This is because further from the centre of the Earth, the pull of gravity is slightly weaker, and it is the pull of gravity on your body that creates its weight. 5. Answers will vary, but suggested responses include (a) Gravity is pulling the boy down and keeping him on the ground. (b) Gravity is pulling down on the cone, but the boy is holding it, preventing it from falling. (c) Gravity has pulled the ice-cream to the ground. It has stopped moving because the ground is preventing it from falling further. 6. Answers will vary. Students should mention that without gravity, the human body would be different—weight-bearing bones and muscles would not be developed. People would float rather than run or walk to move around. Science as a Human Endeavour question Use and influence of science Astronauts experience changes in blood flow, muscle and bone strength and balance among other things. They exercise to prevent some of these effects.

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Background information

Page 136

• Gravitropism is movement or growth by a plant or fungus in response to gravity. Roots tend to grow in the direction of gravitational pull and stems grow in the opposite direction. • The atmosphere and the water in the oceans, lakes and rivers are held on Earth by its gravity.

Preparation

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• Useful websites: − <http://www.rigb.org/insideout/space/beyond/planetx.html> (an interactive activity where students can see the effect of increasing or decreasing the amount of gravity on the possibility of life) − <http://oceanservice.noaa.gov/education/kits/tides/media/ supp_tide06a.html> (an animation of how the moon and sun interact to create different tides on Earth)

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• Students will need access to the internet to complete the activity on page 137.

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The lessons

• Show the students an object, then drop it. Ask them to share their ideas of what is happening when it is dropped. Then read the text. Some students might need to further discuss terms such as 'matter', 'mass' and 'force'.

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1.–2.

Teacher check. Results should show that the balls usually reach the bottom of the ramp at the same time. 3. Differences in the test results could have been caused by the marbles not being released at the same time from the same height, and an uneven surface. 4. The tests were repeated for accuracy.

• The aim of the activity on page 137 is for students to experiment with the way objects are pulled by gravity equally, regardless of weight. The experiment has been designed to remove air resistance as much as possible, although teachers might want to discuss this and how it affects falling objects. Air resistance modifies motion, especially in the fall of a light object, such as a feather. AUSTRALIAN CURRICULUM SCIENCE

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What does gravity do to things on Earth? – 1 You’ve probably heard of gravity – an invisible ‘thing’ that makes things fall down instead of up and stops us floating off into space. But what is gravity and how does it affect objects on Earth? Nobody knows exactly what gravity is. In the 1860s, English scientist Sir Isaac Newton wrote the ‘Law of universal gravitation’. In it he first described gravitational force as an attraction between any two objects, anywhere in the universe (no matter how big or small) towards each other. The strength of that attraction depends on the mass (the amount of matter or material) of the objects, and the distance between them. Your mass attracts other objects to you, but is too little for the force to be very strong. Gravity becomes noticeable when there is a massive object, such as a planet. Earth has a large mass and a powerful gravity that attracts smaller objects to its centre.

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Thrown sideways

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All objects on, or near, Earth are constantly pulled towards the centre of Earth, or downwards, by gravity. If you throw a ball, it will travel for a distance before gravity pulls the ball to the Earth’s surface. If you let go of a ball (or any other object), it will keep falling, pulled closer to the centre of the Earth until it is stopped by something, like the ground. Once Dropped it stops, gravity still pulls down on it, but as there is nowhere for it to go, it stays still. Gravity causes rocks, soil, snow and other materials that are not being held up by something to ‘fall’. Buildings have to be built taking gravity into account. If walls are not built straight, or if the building is built on sloping ground, the force of gravity acting down could cause the building to become unstable or fall.

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Gravity affects living things. Plants and animals are accustomed to the constant force of gravity and are shaped and function based on its presence. Plants use gravity to grow—roots usually grow towards the pull of gravity, and shoots and stems grow against it. Gravity also pulls water down into the soil, draining it for roots to collect underground. Gravity pulling on anything with mass gives it weight. The more mass, the greater the pull of gravity, so the greater weight. Without gravity, cars would be light enough for you to lift! But because Earth’s gravity gives things weight, we have to move and lift things (even our own body and body parts) everyday, so we have muscles and bones designed to help us do this. Astronauts living in space, where there is very little gravity, have no weight. They float around and don’t use leg muscles to walk, run or stand, so muscles and bones used for these actions become weaker over time. Although gravity is not fully understood, it constantly affects everything on Earth. R.I.C. Publications®

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Without gravity, the water in oceans, rivers and lakes on Earth would escape into space. Gravity also creates waterfalls, rain and some kinds of waves. The gravity caused by the moon affects water on Earth. Although the moon is smaller than Earth, it still has gravity. The moon is close enough to Earth that it attracts the Earth, just as the Earth attracts the moon, pulling the Earth towards it. The bodies of water are pulled and moved by the moon’s gravity, helping to create ocean tides.

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Gravity affects the way things move. It makes it harder to move things uphill, against the pull of gravity. For planes to take off and fly, they need to work to overcome the forces of gravity pulling them down. The closer an object is to the centre of Earth, the stronger the attraction, so things further from the earth’s centre experience a lesser pull of gravity. On the top of the highest mountain, gravity is slightly weaker than at sea level.

What does gravity do to things on Earth? – 2 Use the text on page 135 to complete the following. 1. Draw a line to match each word to its definition (a)

mass

•

• English scientist who wrote the universal law of gravitation

(b)

weight

•

• rise and fall of the sea due to the attraction of the moon (and sun)

(c)

gravity

•

• a force attracting objects toward the centre of the earth or toward any other object with mass

(d)

Newton •

(e)

tides

r o e t s Bo r e p ok u S • the amount of matter that an object contains

•

• the amount of force of gravity on an object with mass

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2. What is one effect of the moon’s gravity on Earth?

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3. Describe the role of gravity in the growth of plants.

4. If there is less gravitational pull further from the centre of the Earth, and the pull of gravity creates your weight, would your weight change if you were on the top of Mt Everest (the highest mountain)? If so, how?

the boy

(b)

the ice-cream cone

(c)

the ice-cream

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(a)

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5. Look at the picture and describe at least one effect of gravity on:

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6. Write three ways you might look or act differently if gravity was not present.

Use the internet to find out how astronauts' bodies change in space, and how they try to prevent these changes. Try < http://library.thinkquest.org/C003763/index.php?page=adapt02 > or <http://www.esa.int/esaKIDSen/SEMOD6XDE2E_UsefulSpace_0.html>. AUSTRALIAN CURRICULUM SCIENCE

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Does gravity work the same on all objects? Galileo Galilei examined the way objects fell down to Earth in the 1600s. Legend has it he dropped heavy and light balls at the same time from the top of the leaning tower of Pisa. He noted that they hit the ground at the same time. He found that the speed of these falling heavy and light objects increased at the same, constant rate. The following experiment will test this theory. Does gravity pull a heavy and light object down a ramp to the Earth at the same rate so that they reach the bottom at the same time? Materials: â&#x20AC;˘ objects to create a low, flat ramp (such as a table with one side raised slightly, or a short plank of wood with a book under one end)

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â&#x20AC;˘ one large and one small marble â&#x20AC;˘ a ruler

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Procedure:

í˘ą Make a ramp with a gentle slope. Ensure the surface is flat and even.

í˘˛ Place the ruler along the top.

í˘ł Line the two marbles up behind the ruler. Ensure they are at exactly the same height. í˘´ Lift the ruler up quickly so the marbles start rolling at exactly the same time.

ÂŠ R. I . C.Publ i cat i ons f or4r evi ewyour presults ur p os eso y Do theâ&#x20AC;˘ experiment times. Record below, writing â&#x20AC;&#x2DC;bigâ&#x20AC;&#x2122;n if l the bigâ&#x20AC;˘ marble landed

í˘ľ Watch closely to observe if one marble reaches the bottom of the ramp first, or if they both land at the same time.

í˘ś

Results

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Questions:

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Test 2

Test 3

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first, â&#x20AC;&#x2DC;smallâ&#x20AC;&#x2122; if the small marble landed first, or â&#x20AC;&#x2DC;sameâ&#x20AC;&#x2122; if both marbles reached the bottom of the ramp at the same time.

Test 4

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1. Were the results the same each time?

3. What could have caused any differences in the test results?

4. Why did you need to repeat the experiment 4 times?

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2. Summarise your results.

Why do planets go around the sun? Content focus: Inquiry skills focus:

The lessons

How the sun’s gravity keeps planets in orbit

• Ensure the students understand terms such as 'force', 'mass' and 'gravity'. If possible, complete pages 134-137 before doing this set of pages.

Planning and conducting Processing and analysing data and information Evaluating Communicating

Background information

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• While the sun pulls the planets in, the planets are also moving ‘sideways’ because of their velocity. Their velocity is enough to prevent them from falling into the sun. The sun’s gravity acts instead as a centripetal force, causing the planets to move in a circle. (The centripetal force is not a new force, it is any force that keeps something turning in a circle, such as tension, gravity or friction.) • The sun’s gravity works a bit like a hand swinging a weight on the end of a string. The hand pulls the weight in while it moves. The velocity of the weight keeps it going round. Without the pull of the hand on the string, it would go flying off in a straight line. Similarly, the gravity of the sun pulls the planets in, but their velocity keeps them going round, and without the sun’s gravity the planets would go off in a straight line.

Answers

Page 140

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• Gravity exists throughout the universe, attracting objects with mass towards one another. The strength of the pull depends on the distance between the objects and the amount of mass. The more massive an object, the bigger the gravitational pull. Having a very large mass, the sun exerts the strongest gravitational pull, holding the planetary bodies of our solar system in place.

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• The aim of the activity on page 141 is for students to experiment with gravity, velocity, orbits and centripetal force. The activity should be done outside. When the student in the rope moves, the two rope holders must pull harder (exerting a centripetal force). When the ball is released, it should travel in a straight line, in the exact direction it was travelling at the time it was released, as per Newton’s first law of motion. Discuss any different results that might have been found, and ways the activity could have been done to get more accurate results.

1. (a) 2. A planet’s orbit is the regular, repeating elliptical path it takes around the sun. 3. (c) the sun’s gravity 4. (b) movement 5. (c) 40 000 km/hr 6. The exact phrasing of each student’s answer will differ; however, they should indicate that each planet has enough velocity to keep it falling around, instead of into, the sun. 7. Answers will vary but should indicate that it might move away from the sun and go further out into space. 8. The sun has a lot of planets orbiting it because of its large mass and the gravity that mass creates. 9. (a) Ball 3 (b) Ball 1 (c) Ball 2 Science as a Human Endeavour question Nature and development of science Nicolaus Copernicus stated that the sun does not revolve around the Earth, as people thought at the time, but that the Earth revolves around the sun.

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• Outer planets have slower average orbital speeds than inner planets. Closer to the sun, the pull of gravity is very strong, so a planet needs more speed to stay in orbit. If the planet does not move fast enough, gravity would cause it to fall into the Sun. • Useful websites: − <http://www.teachersdomain.org/asset/ess05_vid_moonorbit/> (a video showing how the moon stays in orbit around the Earth) − < http://spaceplace.nasa.gov/review/how-orbits-work/> (an interactive activity demonstrating how orbits work using cannon imagery)

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Page 141

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• Students will need access to the internet to answer the ‘Science as a human endeavour’ question on page 140.

1. (a) the Earth – the student moving, holding the ball (b) the sun – the two students holding the rope. (c) centripetal force – the rope 2. As the student moved faster around, the two students holding the rope would have had to work harder to keep hold of the rope (pulled harder), and also turned faster. 3.

• For the activity on page 141, teachers will need to obtain a rope, basketball (or other ball) and chalk. This activity will need to be done outside or in a large undercover area. Exercise caution.

4. (c)

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Why do planets go around the sun? – 1 Earth is one of eight planets which many people believe formed billions of years ago, from a rotating cloud of gas and dust which spun around a newly-forming star. From this cloud, rocks collected together into larger and larger objects, eventually becoming the planets of our solar system. These planets are still moving around that star, our sun, in regular, repeating elliptical (elongated, circle-shaped) paths around the sun, called orbits. Why did this cloud of gas and dust spin around the sun, instead of spinning off into space? What keeps these planets, formed from that cloud, still spinning around the sun? The answer to both these questions is gravity.

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Gravity is a force that exists throughout the universe, attracting any two objects with mass to each other. The more mass an object has, the more gravity it will exert on objects around it. The sun is very large (in comparison to the planets around it) and has a lot of mass. This size and mass gives it a lot of gravity, much greater than that of any of the planets in the solar system; enough in fact, to ’hold’ the whole solar system together. The eight planets are kept in the solar system, instead of moving off into space, because of the sun’s gravity. It pulls them, and all other objects near it, towards its centre. If the sun’s gravity is pulling everything to its centre, you might wonder why the planets go around the sun, at a certain distance, instead of getting pulled straight into its centre. Sir Isaac Newton’s work helps us to understand this. He used the imaginary image of a cannon firing a cannon ball around the Earth to help visualise how gravity works to keep objects in orbit. Essentially, it all depends on the object’s velocity (how fast it is moving in a certain direction). Ball 1 shows how, if the object has little velocity, gravity will be strong enough to pull it back to the Earth’s surface. This is what happens when you throw a ball.

Ball 1

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Earth’s gravity at every point along its path, but is moving fast enough to keep going around the curved shape of the Earth without hitting the ground—into orbit. Gravity works as a centripetal force, a force directed towards the centre of a circular or spherical object that makes another object move in a curved path. To orbit Earth without falling, a space shuttle travels at speeds of around 27 000 km/h.

Ball 2

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Thanks to Newton, we know that once objects start moving, they keep moving at the same speed and direction, and don’t stop or change that movement unless new forces act on them. The planets of the solar system, formed from moving pieces in the spinning cloud of gas and dust, have always been moving with speed and direction which orbit won’t change unless the forces involved change. The planets will keep moving around the sun like cannonball 2, with the sun’s gravity as the centripetal force which keeps them in orbit. They have enough velocity to keep moving around the Sun sun without being pulled in, but are not moving fast enough to escape the sun’s gravity. If not for the sun, with its curved Planet shape and enormous gravity, the planets would have moved centripetal away into space. force velocity

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Ball 3 demonstrates what will happen if the velocity is greater still; an object will be able to leave Earth’s gravity and head out into space. This is called escape velocity.

Why do planets go around the sun? – 2

Earth’s Orbit Sun

Use the text on page 139 to answer the questions.

Earth

Moon

1. Tick the most elliptical shape. (a)

(b)

(c)

(d)

2. What is a planet’s orbit?

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3. What provides the centripetal force pulling towards the centre of the sun that causes the planets to move in a circular or curved path around it? (a)

orbits

(b) velocity

(c)

the sun’s gravity

’An object’s velocity is the speed and direction of its ...’ (a)

gravity.

(b) movement.

(c)

force.

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4. Which is the correct ending to this sentence?

(d) escape.

5. Assuming a space shuttle orbits Earth at speeds of around 27 000 km/h, which of the following speeds is most likely to be the escape velocity of Earth? (a)

27 000 km/h

(b) 4 000 m/h

(c)

40 000 km/h

6. What keeps the planets in the solar system from falling into the sun because of its strong gravity?

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8. Why does the sun have so many planets in orbit around it?

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7. What might happen if Earth moved faster through space than it does now?

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9. Using the cannonball picture on page 139, write which ball (Ball 1, Ball 2 or Ball 3) describes the movement of the following three objects: (a)

The Voyager space craft exploring the outer solar system

(b)

A bullet fired from a gun

(c)

A communications satellite Use the internet to find out how Nicolaus Copernicus’s ideas and research into the how the Earth and sun move in space changed people’s understanding of the world.

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Students in orbit Feel the forces at play in space with this activity. Materials: • 1 thick rope, approximately 4 m long • 1 basketball • chalk Instructions:

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5. The person with the ball starts to move, keeping the rope taut. He or she moves faster, moving at a rapid but controllable pace.

1. Draw a large circle (about the size of a hoop) with chalk on the ground.

6. The two people holding the rope need to turn with the person moving, holding tight.

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2. Stretch the rope on the ground, with the 2 ends inside the circle and the looped middle straight out. 3. Two people stand inside the hoop holding onto the ends of the rope.

7. At a certain point, the person moving lets go of the ball, without throwing it. Watch and remember which way the ball goes.

4. A third person stands inside the loop of the stretched out rope, with the loop around his or her waist, holding a basketball.

Questions:

the Earth

•

the two students holding the rope

(b)

the sun

•

the rope

(c)

centripetal force •

•

the student moving, holding the ball

w ww

(a)

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2. What happened to the two people holding the rope as the moving student moved faster?

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3. Draw an arrow to show which direction the ball went when it was released.

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4. According to Newton’s first law of motion, an object will move in a straight line unless acted on by an unbalanced force. This is shown in this activity when: (a)

as the ball was released, the force that kept it moving in a circle was removed, so it was free to travel in a straight line.

(b)

the ball kept moving in a circle because the inward pull of the rope acted as an unbalanced force, keeping the ball travelling in a circle instead of a straight line.

(c)

both (a) and (b). 141

AUSTRALIAN CURRICULUM SCIENCE

Physical sciences

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